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46 - Databases Overview and Environment Setup/005 PostgreSQL Overview & Installation (including pgAdmin installation)_en.srt

@@ -0,0 +1,852 @@
+1
+00:00:06,000 --> 00:00:10,000
+Hello, dissonance in previous lesson, we hold an overview of my sequel.
+
+2
+00:00:10,000 --> 00:00:17,000
+Also, we installed it on our laptops, but in this lesson, I would like to refuse you another popular
+
+3
+00:00:17,000 --> 00:00:21,000
+database management system that is called PostgreSQL.
+
+4
+00:00:22,000 --> 00:00:29,000
+We're going to study this lesson from general overview of PostgreSQL and its main features after you
+
+5
+00:00:29,000 --> 00:00:32,000
+become a little bit familiar to this relational database management system.
+
+6
+00:00:33,000 --> 00:00:35,000
+We'll proceed with practical cause of the lesson.
+
+7
+00:00:36,000 --> 00:00:43,000
+We're going to install is you progress SQL Server e.g. admin stack builder and come online tools.
+
+8
+00:00:43,000 --> 00:00:49,000
+The goal of our lesson is to make sure that your environment is ready for further learning of databases.
+
+9
+00:00:50,000 --> 00:00:54,000
+So I will explain you how to connect the database using Pidgey admin.
+
+10
+00:00:55,000 --> 00:01:00,000
+I'm going to show you how to create new connections to other PostgreSQL servers.
+
+11
+00:01:00,000 --> 00:01:01,000
+And then there was a lesson.
+
+12
+00:01:01,000 --> 00:01:06,000
+You will also understand how to manage progress SQL Windows service.
+
+13
+00:01:06,000 --> 00:01:08,000
+We have a lot of plans for this lesson.
+
+14
+00:01:08,000 --> 00:01:10,000
+Let's get it started.
+
+15
+00:01:11,000 --> 00:01:17,000
+PostgreSQL is a powerful open source object, relational database management system that uses and extends
+
+16
+00:01:17,000 --> 00:01:20,000
+the sequel then which combined with many features.
+
+17
+00:01:21,000 --> 00:01:25,000
+Let's safely store and skills the most complicated data workloads.
+
+18
+00:01:25,000 --> 00:01:33,000
+It's also worth dimensions of possibly a sequel has come a long way since 1986, when it was part of
+
+19
+00:01:33,000 --> 00:01:40,000
+the PostgreSQL project as the University of California at Berkeley and has more than 30 years of active
+
+20
+00:01:40,000 --> 00:01:42,000
+development on the core platform.
+
+21
+00:01:42,000 --> 00:01:48,000
+What a sequel is not controlled by any corporation or other private entity, and the source code is
+
+22
+00:01:48,000 --> 00:01:50,000
+available free of charge.
+
+23
+00:01:50,000 --> 00:01:57,000
+PostgreSQL is loved by many developers across all over the world because it has earned a strong reputation
+
+24
+00:01:57,000 --> 00:02:04,000
+for its proven architecture, reliability, data integrity, robust feature, set extensibility and
+
+25
+00:02:04,000 --> 00:02:10,000
+so dedication of the open source community behind the software to consistently deliver performant and
+
+26
+00:02:10,000 --> 00:02:11,000
+innovative solutions.
+
+27
+00:02:12,000 --> 00:02:16,000
+The sequel is cross-platform, and it runs on all major operating systems.
+
+28
+00:02:17,000 --> 00:02:24,000
+Also, it is Transaction's compliant since 2001, and this powerful add ons such as the popular post
+
+29
+00:02:24,000 --> 00:02:27,000
+use spatial database extender.
+
+30
+00:02:27,000 --> 00:02:33,000
+It is no surprise that possibly a sequel has become the open source relational database of choice for
+
+31
+00:02:33,000 --> 00:02:35,000
+many people and organizations.
+
+32
+00:02:35,000 --> 00:02:36,000
+It was great.
+
+33
+00:02:36,000 --> 00:02:43,000
+Sequel comes with many features aimed to help developers build applications administrators to protect
+
+34
+00:02:43,000 --> 00:02:49,000
+data integrity and build fault tolerant environments and help you manage your data no matter how big
+
+35
+00:02:49,000 --> 00:02:51,000
+or small the data set.
+
+36
+00:02:51,000 --> 00:02:58,000
+And on top of all things that we have already discussed about possible SQL, it is also highly extensible.
+
+37
+00:02:58,000 --> 00:03:00,000
+What does this mean?
+
+38
+00:03:00,000 --> 00:03:07,000
+For example, you can define your own data types, build out custom functions, even write code from
+
+39
+00:03:07,000 --> 00:03:11,000
+different programming languages without compiling your database.
+
+40
+00:03:11,000 --> 00:03:16,000
+Pretty cool features, don't you think so is a lesson about my school?
+
+41
+00:03:16,000 --> 00:03:23,000
+We also discussed on the high level existence standards for sequel structured query language, and also
+
+42
+00:03:23,000 --> 00:03:27,000
+we mention is that each database management system may have its own dialect.
+
+43
+00:03:28,000 --> 00:03:35,000
+Dialect includes some minor differences in syntax lack of the stated on the PostgreSQL Oracle website,
+
+44
+00:03:35,000 --> 00:03:42,000
+possibly a tries to conform with the school's standards where such conformance doesn't contradict traditional
+
+45
+00:03:42,000 --> 00:03:46,000
+features or could lead to pure architectural decisions.
+
+46
+00:03:47,000 --> 00:03:52,000
+Still, it is not always clear how syntax differences may impact on architectural decisions.
+
+47
+00:03:52,000 --> 00:03:54,000
+My subjective opinion?
+
+48
+00:03:54,000 --> 00:03:59,000
+This is just inheritance from times when there were no standards for school.
+
+49
+00:03:59,000 --> 00:04:06,000
+And as you already know, PostgreSQL is not a new project as a conclusion of dialogue differences.
+
+50
+00:04:06,000 --> 00:04:12,000
+I'd like to say that many of the features required by the school standards are supported, though sometimes
+
+51
+00:04:12,000 --> 00:04:15,000
+with slightly different syntax or function.
+
+52
+00:04:16,000 --> 00:04:18,000
+Let's review core features of a sequel.
+
+53
+00:04:19,000 --> 00:04:26,000
+Among the features, it is worse dimensions next one's data types, customizations, composite custom
+
+54
+00:04:26,000 --> 00:04:34,000
+types just in time compilation of expressions Sophisticated Keyword Planner Optimizer Index only scans
+
+55
+00:04:35,000 --> 00:04:45,000
+multi columns statistics advanced indexing point in time recovery active standbys replication asynchronous
+
+56
+00:04:45,000 --> 00:04:53,000
+synchronous logical right that log in syndication features multifactor authentication with certificates
+
+57
+00:04:54,000 --> 00:04:58,000
+and an additional massive support of procedural languages.
+
+58
+00:04:59,000 --> 00:05:07,000
+Sequel Jason Pass Expressions for data wrappers connect to other databases or streams was a standard
+
+59
+00:05:07,000 --> 00:05:14,000
+sequel interface many extensions that provide additional functionality, including Porzingis.
+
+60
+00:05:14,000 --> 00:05:18,000
+These are just some of the features that you can find in possibly a sequel.
+
+61
+00:05:19,000 --> 00:05:19,000
+Probably.
+
+62
+00:05:19,000 --> 00:05:24,000
+We can say that you already have an impression about PostgreSQL, and yes, you are right.
+
+63
+00:05:25,000 --> 00:05:27,000
+This is also called database management system.
+
+64
+00:05:28,000 --> 00:05:34,000
+This is one of the reasons why it's become popular, so let's now install it on our computers.
+
+65
+00:05:35,000 --> 00:05:40,000
+The first thing that we need to do is to download distribution back for your operating system.
+
+66
+00:05:41,000 --> 00:05:45,000
+You can find a link to the download page in attachments to this lesson.
+
+67
+00:05:45,000 --> 00:05:52,000
+You can find isn't active installer or zip archive was binaries for this tutorial and personally for
+
+68
+00:05:52,000 --> 00:05:55,000
+myself, I would download Interactive Installer.
+
+69
+00:05:56,000 --> 00:06:00,000
+I don't want to play hacker game and console to extract binaries.
+
+70
+00:06:00,000 --> 00:06:03,000
+Also, all examples from the slide off of Windows.
+
+71
+00:06:04,000 --> 00:06:07,000
+The similar stabs during the installation for Mac OS.
+
+72
+00:06:08,000 --> 00:06:10,000
+But just in case you can also.
+
+73
+00:06:10,000 --> 00:06:14,000
+Lines and attachments guide on how to install PostgreSQL on Mac.
+
+74
+00:06:15,000 --> 00:06:21,000
+Basically, after you selected your operating system, there is a separate page where you can select
+
+75
+00:06:21,000 --> 00:06:25,000
+what you would like to do, not binaries or installer.
+
+76
+00:06:25,000 --> 00:06:29,000
+You can make a cup of tea because downloading may take some time.
+
+77
+00:06:30,000 --> 00:06:31,000
+Once downloading is finished.
+
+78
+00:06:31,000 --> 00:06:35,000
+Runs interactive installer on the first step.
+
+79
+00:06:35,000 --> 00:06:36,000
+There is nothing special.
+
+80
+00:06:36,000 --> 00:06:37,000
+Just welcome message.
+
+81
+00:06:38,000 --> 00:06:39,000
+Click Next button.
+
+82
+00:06:40,000 --> 00:06:44,000
+On the next step, make sure you say it's a installation directory.
+
+83
+00:06:44,000 --> 00:06:47,000
+Once you are ready, click the next button.
+
+84
+00:06:48,000 --> 00:06:53,000
+On this step, we have to select PostgreSQL components that we want to install.
+
+85
+00:06:53,000 --> 00:06:56,000
+Let me explain you a little bit about each of this.
+
+86
+00:06:57,000 --> 00:07:01,000
+Well, PostgreSQL server, it is our core component.
+
+87
+00:07:01,000 --> 00:07:03,000
+You can treat it as databases.
+
+88
+00:07:03,000 --> 00:07:09,000
+So DG Admin is a client you are to interact with supposedly a SQL server.
+
+89
+00:07:10,000 --> 00:07:16,000
+The Stack Builder utility provides a graphical interface that simplifies the process of downloading
+
+90
+00:07:16,000 --> 00:07:21,000
+and installing modules that complement your Cosmos sequel installation.
+
+91
+00:07:22,000 --> 00:07:28,000
+When you install a module with Stack Builder, Stack Builder automatically resolves any software dependencies.
+
+92
+00:07:29,000 --> 00:07:36,000
+So this nice tool to have installed just in case and another component is a command line tools that
+
+93
+00:07:36,000 --> 00:07:40,000
+they use to interact with PostgreSQL with the help of command line.
+
+94
+00:07:41,000 --> 00:07:44,000
+I recommend you also to install this just in case.
+
+95
+00:07:45,000 --> 00:07:47,000
+After that, click next button.
+
+96
+00:07:47,000 --> 00:07:53,000
+After that, you have opportunity to configure passed as a folder where your data will be stored.
+
+97
+00:07:54,000 --> 00:08:00,000
+By default, you will be offered to create a data folder in PostgreSQL Installation Directory.
+
+98
+00:08:01,000 --> 00:08:04,000
+If this is OK for you, then just press next button.
+
+99
+00:08:05,000 --> 00:08:13,000
+On the next step, please write a password for a super user who has all rights in database having access
+
+100
+00:08:13,000 --> 00:08:19,000
+to this user, you can start creation of other users, schemas, tables and so on.
+
+101
+00:08:19,000 --> 00:08:21,000
+Please remember this password.
+
+102
+00:08:22,000 --> 00:08:23,000
+This is important.
+
+103
+00:08:24,000 --> 00:08:31,000
+Was Great Article is an app that will be running on our computer and to get connected to the PostgreSQL,
+
+104
+00:08:31,000 --> 00:08:34,000
+we need to know port number on this computer.
+
+105
+00:08:35,000 --> 00:08:40,000
+And the biggest lesson when we installed my I explained what is port number.
+
+106
+00:08:41,000 --> 00:08:46,000
+Also, I have separate course about that programming where I cover network concept.
+
+107
+00:08:46,000 --> 00:08:48,000
+Just to remind you a few words about Port.
+
+108
+00:08:48,000 --> 00:08:49,000
+No.
+
+109
+00:08:49,000 --> 00:08:52,000
+We are going to use it as part of address.
+
+110
+00:08:52,000 --> 00:09:00,000
+One will connect to the possible SQL server, and if IP address is an address of our machines network,
+
+111
+00:09:01,000 --> 00:09:05,000
+then port number is an address of the app on this specific machine.
+
+112
+00:09:06,000 --> 00:09:14,000
+The default port, of course, with a sequel, is 54 so that you can change it if you wish.
+
+113
+00:09:14,000 --> 00:09:20,000
+And if for some reason this sport is already captured by other app, in my case, I just click next
+
+114
+00:09:21,000 --> 00:09:24,000
+select lock collar that works the best for you.
+
+115
+00:09:25,000 --> 00:09:29,000
+This configuration will impact all the collaboration settings of the app.
+
+116
+00:09:29,000 --> 00:09:32,000
+Don't worry, you will be able to change this later, too.
+
+117
+00:09:33,000 --> 00:09:40,000
+You can keep the folder color option and click Next button on this snap check installation information.
+
+118
+00:09:40,000 --> 00:09:46,000
+And if everything looks good to you, press it to the next step and start installation.
+
+119
+00:09:47,000 --> 00:09:52,000
+If installation finished successfully, you would see a notification about installation completion.
+
+120
+00:09:53,000 --> 00:09:55,000
+You will be offered the launch stack builder.
+
+121
+00:09:56,000 --> 00:09:58,000
+You can keep this checkbox marked if you wish.
+
+122
+00:09:59,000 --> 00:10:02,000
+And afterwards, just press finish button.
+
+123
+00:10:02,000 --> 00:10:03,000
+And that's it.
+
+124
+00:10:03,000 --> 00:10:09,000
+Congrats, PostgreSQL installed on your computer with all other components.
+
+125
+00:10:09,000 --> 00:10:15,000
+So in case you kept chequebooks smart, you would have struggled to open.
+
+126
+00:10:15,000 --> 00:10:18,000
+But what to do with it in the future?
+
+127
+00:10:18,000 --> 00:10:25,000
+You can run it separately in case you want to install some advanced PostgreSQL, for example.
+
+128
+00:10:25,000 --> 00:10:29,000
+On the slide, you can see just an example of what can be installed.
+
+129
+00:10:30,000 --> 00:10:33,000
+We don't need anything from this list at this moment.
+
+130
+00:10:33,000 --> 00:10:35,000
+Sewa Just Glow Stack Builder.
+
+131
+00:10:36,000 --> 00:10:43,000
+Let's understand now how to run PostgreSQL, and let's test that interaction with databases is configured
+
+132
+00:10:43,000 --> 00:10:43,000
+properly.
+
+133
+00:10:44,000 --> 00:10:50,000
+And various lessons, I also explained you what Windows service is just to remind you.
+
+134
+00:10:50,000 --> 00:10:58,000
+Windows services are core components of the Microsoft Windows operating system and enables the creation
+
+135
+00:10:58,000 --> 00:11:02,000
+and management of long running processes right after installation.
+
+136
+00:11:03,000 --> 00:11:06,000
+You have PostgreSQL Windows service up and running.
+
+137
+00:11:06,000 --> 00:11:10,000
+You can check this by opening services on your Windows machine.
+
+138
+00:11:10,000 --> 00:11:16,000
+Also in this place, you can either stop the service or configure startup time.
+
+139
+00:11:16,000 --> 00:11:23,000
+For example, I keep my school service started automatically, started that and my PostgreSQL service
+
+140
+00:11:23,000 --> 00:11:29,000
+I keep in manual starts up because I don't see a lot of reasons to load.
+
+141
+00:11:29,000 --> 00:11:32,000
+My machine was to databases run in Perl.
+
+142
+00:11:32,000 --> 00:11:36,000
+Definitely for this demo I turned PostgreSQL service on.
+
+143
+00:11:37,000 --> 00:11:40,000
+Now you know the place where this may be configured.
+
+144
+00:11:41,000 --> 00:11:41,000
+Great.
+
+145
+00:11:42,000 --> 00:11:46,000
+Now, let's learn how to work with supposedly equals through the nice UI.
+
+146
+00:11:46,000 --> 00:11:53,000
+We have separate applications that we have also already installed and that the so-called admin to start
+
+147
+00:11:53,000 --> 00:11:57,000
+at least navigate to the installation directory of possible sequel.
+
+148
+00:11:58,000 --> 00:12:01,000
+You're going to find a separate folder was named A.G. Admin.
+
+149
+00:12:02,000 --> 00:12:06,000
+Open it and find the executable file with the same name.
+
+150
+00:12:07,000 --> 00:12:11,000
+Double click it and Beijing admin app will start loading.
+
+151
+00:12:12,000 --> 00:12:16,000
+On the first start up, you will be asked to set and must have passwords for page admin.
+
+152
+00:12:17,000 --> 00:12:23,000
+This is needed because potentially you can have multiple connections and server configuration stored
+
+153
+00:12:23,000 --> 00:12:26,000
+in the app to secure the setup on each startup.
+
+154
+00:12:26,000 --> 00:12:34,000
+This app will ask you a master password, so also remember the password and press OK button?
+
+155
+00:12:35,000 --> 00:12:38,000
+The next thing that we need to do is to connect through an existing server.
+
+156
+00:12:38,000 --> 00:12:40,000
+We have page admin.
+
+157
+00:12:40,000 --> 00:12:47,000
+You just need to expand servers in the left panel and you will find the server that's already exists
+
+158
+00:12:47,000 --> 00:12:48,000
+on your local hosts.
+
+159
+00:12:49,000 --> 00:12:52,000
+This is exactly the server that we have just installed.
+
+160
+00:12:52,000 --> 00:12:59,000
+Click on it and you will be prompted to enter your password and to share passwords with you, said during
+
+161
+00:12:59,000 --> 00:13:00,000
+the installation.
+
+162
+00:13:01,000 --> 00:13:04,000
+You can save passwords in page admin if you wish.
+
+163
+00:13:04,000 --> 00:13:06,000
+And press OK button.
+
+164
+00:13:07,000 --> 00:13:08,000
+Congrats, team.
+
+165
+00:13:08,000 --> 00:13:10,000
+We managed to connect to our Sara.
+
+166
+00:13:11,000 --> 00:13:17,000
+That is great on the home page, you can see some charts and information about performance.
+
+167
+00:13:17,000 --> 00:13:21,000
+There are also a lot of other things that we can do from this point.
+
+168
+00:13:21,000 --> 00:13:25,000
+But all of this will be discussed in separate lessons in details.
+
+169
+00:13:26,000 --> 00:13:31,000
+The most important thing is that you successfully managed to connect as a possible SQL server.
+
+170
+00:13:32,000 --> 00:13:34,000
+Let me show you one more interesting thing.
+
+171
+00:13:34,000 --> 00:13:40,000
+You can always connect the remote database knowing the exact address of the PostgreSQL.
+
+172
+00:13:41,000 --> 00:13:48,000
+Let me show you now how to add new silver collection service and then click Add New Server.
+
+173
+00:13:49,000 --> 00:13:56,000
+Now we need just some information about servers that we want to connect on the general tap.
+
+174
+00:13:56,000 --> 00:14:01,000
+Just enter the names that would be easy to recognize for you and Server Group.
+
+175
+00:14:01,000 --> 00:14:07,000
+You can group different service together to navigate easily between them later when needed.
+
+176
+00:14:08,000 --> 00:14:14,000
+After that, you need to choose connection type to the server and configure it separately in the top
+
+177
+00:14:14,000 --> 00:14:14,000
+bar.
+
+178
+00:14:14,000 --> 00:14:16,000
+You can see different apps.
+
+179
+00:14:16,000 --> 00:14:18,000
+They are connection.
+
+180
+00:14:18,000 --> 00:14:20,000
+This one is for connections.
+
+181
+00:14:20,000 --> 00:14:23,000
+We are TCP IP Protocol SSL.
+
+182
+00:14:24,000 --> 00:14:27,000
+This step is to configure connection with SSL.
+
+183
+00:14:28,000 --> 00:14:30,000
+SSL stands for Secure Sockets Layer.
+
+184
+00:14:31,000 --> 00:14:34,000
+And again, we're going to learn web in a separate course.
+
+185
+00:14:35,000 --> 00:14:40,000
+This protocol runs on top of this IP protocol as a secret tunnel.
+
+186
+00:14:41,000 --> 00:14:44,000
+On that one tab, you can configure SSL connection.
+
+187
+00:14:45,000 --> 00:14:52,000
+In no particular case, I want to use Connection tab to configure connection with TCP IP protocol in
+
+188
+00:14:52,000 --> 00:14:53,000
+host address.
+
+189
+00:14:53,000 --> 00:14:55,000
+You should put the address of the host.
+
+190
+00:14:55,000 --> 00:14:57,000
+Usually, this is an IP address.
+
+191
+00:14:58,000 --> 00:15:01,000
+In this example, I'm going to connect to my localhost.
+
+192
+00:15:02,000 --> 00:15:07,000
+This IP always refers to the local host, or you can just use local hostname.
+
+193
+00:15:07,000 --> 00:15:14,000
+In this particular example, localhost is a hostname which refers to the current computer used to access
+
+194
+00:15:14,000 --> 00:15:14,000
+it.
+
+195
+00:15:15,000 --> 00:15:23,000
+I use default port for possible sequel, so I put value 50 four course suited to in the ports field
+
+196
+00:15:23,000 --> 00:15:25,000
+in maintenance database.
+
+197
+00:15:25,000 --> 00:15:28,000
+Put Pause Grass What is maintenance database?
+
+198
+00:15:28,000 --> 00:15:34,000
+Zip Postgres database is also created when a database cluster is initialized.
+
+199
+00:15:35,000 --> 00:15:41,000
+This database is meant as a default database for users and applications to connect to.
+
+200
+00:15:41,000 --> 00:15:45,000
+After that, we need to specify a name of the user.
+
+201
+00:15:45,000 --> 00:15:49,000
+The name of our admin user by default is progress.
+
+202
+00:15:50,000 --> 00:15:53,000
+Also, we have to use the password for this user.
+
+203
+00:15:53,000 --> 00:15:58,000
+And after all configurations are on, please just click Save button.
+
+204
+00:15:59,000 --> 00:16:02,000
+That's all what I wanted to share with you in this lesson.
+
+205
+00:16:02,000 --> 00:16:08,000
+Let's recap what we have learned today in this lesson we hold PostgreSQL over.
+
+206
+00:16:08,000 --> 00:16:10,000
+You removed its main features.
+
+207
+00:16:11,000 --> 00:16:15,000
+After that, we proceed with the practice space to prepare environment.
+
+208
+00:16:15,000 --> 00:16:21,000
+We installed Postgres, SQL Server, PJ Admin, Stack Builder and command line tools.
+
+209
+00:16:22,000 --> 00:16:25,000
+I showed you an example How to connect to Postgres SQL Server.
+
+210
+00:16:25,000 --> 00:16:30,000
+We are Pidgey admin and how to create a new server inside paging admin.
+
+211
+00:16:31,000 --> 00:16:37,000
+Also, I explained how and where you can configure Windows servers for Postgres sequel.
+
+212
+00:16:38,000 --> 00:16:40,000
+Thank you all team for your attention.
+
+213
+00:16:40,000 --> 00:16:43,000
+Have a great day and see you in the next lesson.
+

46 - Databases Overview and Environment Setup/005 PostgreSQL-download.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://www.postgresql.org/download/

46 - Databases Overview and Environment Setup/external-links.txt

@@ -0,0 +1,12 @@
+
+004 Microsoft-MySQL-Installer
+https://dev.mysql.com/downloads/installer/
+
+004 How-to-Install-MySQL-on-MacOS
+https://dev.mysql.com/doc/refman/8.0/en/macos-installation-pkg.html
+
+005 PostgreSQL-download
+https://www.postgresql.org/download/
+
+005 Guide-How-to-install-PostgreSQL-on-Mac
+https://www.postgresqltutorial.com/install-postgresql-macos/

47 - Relational databases/001 Relational Databases Basic Concepts_en.srt

@@ -0,0 +1,1320 @@
+1
+00:00:05,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:06,000 --> 00:00:10,000
+And this last one, we're going to start learning the relational databases.
+
+3
+00:00:11,000 --> 00:00:17,000
+We're going to start from understanding of basic concepts and gradually we'll move to more complicated
+
+4
+00:00:17,000 --> 00:00:17,000
+topics.
+
+5
+00:00:18,000 --> 00:00:26,000
+We're going to start our lesson with learning such basic terms a stable entity, absolute chapel records,
+
+6
+00:00:26,000 --> 00:00:32,000
+etc. separate focus on the good and the differences between database and schema.
+
+7
+00:00:32,000 --> 00:00:38,000
+Because very often my students ask me what is schema and how it is different from database.
+
+8
+00:00:39,000 --> 00:00:43,000
+After that, we are going to learn such important concept as primary key.
+
+9
+00:00:43,000 --> 00:00:48,000
+I will share with you different examples, and that will help you to understand the difference between
+
+10
+00:00:48,000 --> 00:00:52,000
+simple and compound key, natural and surrogate key.
+
+11
+00:00:53,000 --> 00:00:58,000
+Also, you will learn what alternate care is to understand relationships in databases.
+
+12
+00:00:58,000 --> 00:01:05,000
+We need to learn what foreign key is, and once we learn all these terms will start none of the relationships
+
+13
+00:01:05,000 --> 00:01:06,000
+in relational databases.
+
+14
+00:01:07,000 --> 00:01:12,000
+You're going to understand what types of relationship we have and how they're different from each other.
+
+15
+00:01:13,000 --> 00:01:19,000
+Let's start our lesson before we start dive deeper into the details of relational databases.
+
+16
+00:01:20,000 --> 00:01:25,000
+Let's learn some basic terms that we are going to use during today's lesson and future lessons.
+
+17
+00:01:25,000 --> 00:01:29,000
+Let's go over each channel one by one database.
+
+18
+00:01:30,000 --> 00:01:35,000
+We use this term usually to refer to a set of tables with some data in them.
+
+19
+00:01:36,000 --> 00:01:36,000
+Is that clear?
+
+20
+00:01:37,000 --> 00:01:38,000
+I believe there is one more question.
+
+21
+00:01:39,000 --> 00:01:40,000
+What are tables?
+
+22
+00:01:41,000 --> 00:01:47,000
+Tables and metrics with data of the specified format in table, you have rows and columns.
+
+23
+00:01:47,000 --> 00:01:49,000
+Each column has name.
+
+24
+00:01:49,000 --> 00:01:56,000
+Also, each column has data that we can specify what kind of data will be stored in this column.
+
+25
+00:01:57,000 --> 00:02:03,000
+Topple in relational databases, we use this term to describe one records of data.
+
+26
+00:02:03,000 --> 00:02:06,000
+OK, so what is the records?
+
+27
+00:02:06,000 --> 00:02:09,000
+Records is one row in table.
+
+28
+00:02:09,000 --> 00:02:16,000
+Let's continue with other terms is we need to be familiar with entity and entity is distinguishable.
+
+29
+00:02:16,000 --> 00:02:23,000
+The real world object that exists and the object should not be considered as an entity until it can
+
+30
+00:02:23,000 --> 00:02:27,000
+be easily identified from all other objects of the real world.
+
+31
+00:02:28,000 --> 00:02:36,000
+In other simple words, if you can't identify sets of characteristics that define some object in a unique
+
+32
+00:02:36,000 --> 00:02:43,000
+way, which allows you to store data about objects or if you are not going to retrieve data about some
+
+33
+00:02:43,000 --> 00:02:48,000
+object, then there is no point in creating that entity in a database.
+
+34
+00:02:49,000 --> 00:02:50,000
+Does it make sense?
+
+35
+00:02:51,000 --> 00:02:58,000
+Attribute Attribute is a characteristic in a database management system and attributes refers to database
+
+36
+00:02:58,000 --> 00:03:05,000
+field attributes, describes the characteristics or properties of an entity in a database table and
+
+37
+00:03:05,000 --> 00:03:10,000
+the entity in a database table is defined was a fixed set of actions.
+
+38
+00:03:11,000 --> 00:03:16,000
+For example, you will have to define a user entity that we can define.
+
+39
+00:03:16,000 --> 00:03:20,000
+It was a set of attributes like email, name, etc..
+
+40
+00:03:21,000 --> 00:03:27,000
+The attribute values of each user entity will define its characteristics in the table.
+
+41
+00:03:28,000 --> 00:03:36,000
+In most simple words, attributes are columns in database tables, and each row has set of common values.
+
+42
+00:03:36,000 --> 00:03:40,000
+Those are attributes, but this is very simplified definition.
+
+43
+00:03:41,000 --> 00:03:48,000
+There is also one more chance that we have learned to use often today in the lesson schema analysis
+
+44
+00:03:48,000 --> 00:03:53,000
+schema is an abstract designs its represent the storage of your data in a database.
+
+45
+00:03:53,000 --> 00:04:01,000
+It describes both zircon zation of data and the relationships between tables in a given database.
+
+46
+00:04:01,000 --> 00:04:07,000
+Sometimes you can find that people use schema and database as interchangeable terms.
+
+47
+00:04:07,000 --> 00:04:09,000
+But this is not correct.
+
+48
+00:04:09,000 --> 00:04:16,000
+The fundamental difference between them is that the database is an organized collection of internal
+
+49
+00:04:16,000 --> 00:04:23,000
+data data, and on the other hand, the schema is a logical representation or description of an entire
+
+50
+00:04:23,000 --> 00:04:23,000
+database.
+
+51
+00:04:24,000 --> 00:04:31,000
+Schema contains the structure of tables, attributes that types, constraints and how they relate to
+
+52
+00:04:31,000 --> 00:04:32,000
+other tables.
+
+53
+00:04:32,000 --> 00:04:35,000
+Do you feel the difference between these two terms?
+
+54
+00:04:36,000 --> 00:04:38,000
+These are just basic terms.
+
+55
+00:04:38,000 --> 00:04:39,000
+Tsarist jumps were.
+
+56
+00:04:39,000 --> 00:04:42,000
+I go on to those examples as we go.
+
+57
+00:04:42,000 --> 00:04:43,000
+Is that clear?
+
+58
+00:04:44,000 --> 00:04:46,000
+If yes, then let's proceed.
+
+59
+00:04:47,000 --> 00:04:50,000
+Another important term in a relational databases is a primary key.
+
+60
+00:04:51,000 --> 00:04:58,000
+I decided to dedicate a separate slide to reviews the definition so primary key is a specific choice
+
+61
+00:04:58,000 --> 00:05:00,000
+of minimal set of attributes.
+
+62
+00:05:00,000 --> 00:05:07,000
+And you already know that attributes many columns that uniquely identify, topple and you learn, you
+
+63
+00:05:07,000 --> 00:05:11,000
+know, that tadpole is a synonym to row in the table.
+
+64
+00:05:11,000 --> 00:05:19,000
+In most simple words, primary key is an attribute or unique set of attributes that can identify specific
+
+65
+00:05:19,000 --> 00:05:21,000
+rule in the book, among others.
+
+66
+00:05:22,000 --> 00:05:28,000
+And if you would ask me to come up with even simple definition, I would say is its primary key is a
+
+67
+00:05:28,000 --> 00:05:29,000
+unique idea.
+
+68
+00:05:30,000 --> 00:05:35,000
+We are going to build a relationship between tables and being more specific.
+
+69
+00:05:35,000 --> 00:05:41,000
+We would build relationships with the two in one table with data in another table.
+
+70
+00:05:41,000 --> 00:05:49,000
+That means we need to find a way to uniquely identify each role in each table to connect them between
+
+71
+00:05:49,000 --> 00:05:49,000
+each other.
+
+72
+00:05:50,000 --> 00:05:53,000
+That's why primary key is so important.
+
+73
+00:05:53,000 --> 00:05:56,000
+Let's come up with the ideas of primary key.
+
+74
+00:05:57,000 --> 00:06:03,000
+The first goal is to uniquely identify to people in the database table, and the second goal is to ensure
+
+75
+00:06:03,000 --> 00:06:04,000
+connection between tables.
+
+76
+00:06:05,000 --> 00:06:06,000
+Is that clear?
+
+77
+00:06:06,000 --> 00:06:13,000
+And always remember that in case of any questions exam, you can put your question below this reader
+
+78
+00:06:13,000 --> 00:06:15,000
+and I will be happy to answer it.
+
+79
+00:06:16,000 --> 00:06:23,000
+But how to choose the primary key, among other attributes, what rules should be applied or what is
+
+80
+00:06:23,000 --> 00:06:30,000
+the best practices zero of some is to select the shortest possible field if you understand what I mean.
+
+81
+00:06:30,000 --> 00:06:33,000
+What's the shortest possible combination of fields?
+
+82
+00:06:33,000 --> 00:06:36,000
+By saying this, I pursue one goal.
+
+83
+00:06:36,000 --> 00:06:39,000
+Primary key should be simple enough to work.
+
+84
+00:06:39,000 --> 00:06:44,000
+It should be atomic and shouldn't consist from multiple values inside one field.
+
+85
+00:06:45,000 --> 00:06:50,000
+It should be unique, and achieving this uniqueness shouldn't be hard thing to do.
+
+86
+00:06:51,000 --> 00:06:58,000
+I mean is easy to find, not unique first name, and it is impossible to find the same email.
+
+87
+00:06:58,000 --> 00:07:05,000
+That means that achieving uniqueness for email field is more simple, and it is better option to use
+
+88
+00:07:05,000 --> 00:07:06,000
+for primary key.
+
+89
+00:07:06,000 --> 00:07:10,000
+And obviously, primary key can't be no value.
+
+90
+00:07:11,000 --> 00:07:12,000
+To send my point.
+
+91
+00:07:13,000 --> 00:07:21,000
+Another important classification is its primary key may be simple and compound interest and in simple
+
+92
+00:07:21,000 --> 00:07:25,000
+words, simple primary key consists of the one people felt.
+
+93
+00:07:25,000 --> 00:07:34,000
+This can be an email I the best for no or anything else what is unique for each row in table and fits
+
+94
+00:07:34,000 --> 00:07:35,000
+in one field?
+
+95
+00:07:36,000 --> 00:07:44,000
+On the other hand, Compound's primary key consists of two or more fields, so the combination of these
+
+96
+00:07:44,000 --> 00:07:46,000
+fields should be unique.
+
+97
+00:07:47,000 --> 00:07:54,000
+For example, I have online courses and each course has I.D. That is, of course, primary key.
+
+98
+00:07:54,000 --> 00:08:01,000
+Also, I have students and each student has its own unique identifier, and let's imagine that I need
+
+99
+00:08:01,000 --> 00:08:04,000
+to store information about enrollments.
+
+100
+00:08:04,000 --> 00:08:12,000
+In my course, I have an enrollment table that has Compound's primary key that consists of two values,
+
+101
+00:08:12,000 --> 00:08:21,000
+namely courses plus student I.D. And there is information that people like the date of enrollment,
+
+102
+00:08:21,000 --> 00:08:29,000
+growth, speed, discount applied or any other possible field can be easily connected and identified
+
+103
+00:08:29,000 --> 00:08:31,000
+with this compound primary key.
+
+104
+00:08:31,000 --> 00:08:32,000
+Does it make sense?
+
+105
+00:08:33,000 --> 00:08:39,000
+To be honest, Compound's primary keys are less often than simple primary kiss.
+
+106
+00:08:39,000 --> 00:08:47,000
+But still they exist, and I'm going to teach you how to create compounds primary keys in the database.
+
+107
+00:08:47,000 --> 00:08:50,000
+In a separate lesson, you're in the practice exercise.
+
+108
+00:08:51,000 --> 00:08:55,000
+And that's the classification of primary key depends on its origins.
+
+109
+00:08:56,000 --> 00:09:04,000
+Primary key may be natural a surrogate surrogate primary keys also called synthetic, sometimes in simple
+
+110
+00:09:04,000 --> 00:09:05,000
+words, is a natural primary.
+
+111
+00:09:05,000 --> 00:09:09,000
+Key is a field that stores useful information.
+
+112
+00:09:09,000 --> 00:09:14,000
+For example, desperate number may be unique for a person, but this is also values.
+
+113
+00:09:14,000 --> 00:09:18,000
+It contains information related to specific person.
+
+114
+00:09:18,000 --> 00:09:19,000
+This is real.
+
+115
+00:09:19,000 --> 00:09:24,000
+Data is accurate naturally, and just records the same situation with email.
+
+116
+00:09:25,000 --> 00:09:28,000
+Email may be considered as national primary key.
+
+117
+00:09:29,000 --> 00:09:32,000
+National keys have one logical advantage, in my opinion.
+
+118
+00:09:32,000 --> 00:09:35,000
+It sounds like this is it the search.
+
+119
+00:09:36,000 --> 00:09:42,000
+Since Natural Ki contains some valuable information, it is easier for you to understand this information.
+
+120
+00:09:42,000 --> 00:09:49,000
+For example, it will be hard to remember sequence number for each user to search user, but it's the
+
+121
+00:09:49,000 --> 00:09:56,000
+but instead it will be easier to memorize user email and search user by its email.
+
+122
+00:09:56,000 --> 00:10:04,000
+Natural primary keys have some disadvantages, though the most important are take more memory to store
+
+123
+00:10:04,000 --> 00:10:06,000
+rather than surrogate key.
+
+124
+00:10:07,000 --> 00:10:14,000
+This means that you will require more memory to store the data, and also this means is a joint request
+
+125
+00:10:14,000 --> 00:10:22,000
+on multiple tables might take more time because usually natural keys are strings but not integers,
+
+126
+00:10:22,000 --> 00:10:25,000
+and it takes time to compare strings.
+
+127
+00:10:26,000 --> 00:10:29,000
+Requires cascading update in case of changing.
+
+128
+00:10:29,000 --> 00:10:38,000
+Imagine that you use email as a primary key and user decided to change email, we forbid him to do so.
+
+129
+00:10:39,000 --> 00:10:40,000
+Of course not.
+
+130
+00:10:40,000 --> 00:10:42,000
+He changes email.
+
+131
+00:10:42,000 --> 00:10:49,000
+After that, we have to update email everywhere where we used his primary key to build relationships
+
+132
+00:10:50,000 --> 00:10:52,000
+basically in other tables.
+
+133
+00:10:52,000 --> 00:10:59,000
+Definitely, this operation will take some time dependent on a number of changes that we have to make.
+
+134
+00:11:00,000 --> 00:11:03,000
+But why should we do these cascading changes?
+
+135
+00:11:03,000 --> 00:11:10,000
+If we could avoid doing them at all and one more problems that you might face with while using natural
+
+136
+00:11:10,000 --> 00:11:16,000
+key, there might be cases when you just don't have all the necessary information all the time.
+
+137
+00:11:16,000 --> 00:11:21,000
+Imagine that in the application, you also supports registration with a phone number.
+
+138
+00:11:22,000 --> 00:11:29,000
+User can choose whether he or she wants to use phone number or email for authorization.
+
+139
+00:11:29,000 --> 00:11:31,000
+And what should we do in this case?
+
+140
+00:11:32,000 --> 00:11:33,000
+It is hard to answer.
+
+141
+00:11:33,000 --> 00:11:40,000
+You would have to come up with some email that you don't have in order to fill out the primary key.
+
+142
+00:11:40,000 --> 00:11:46,000
+And what will happen when you start sending you say that you are going to send an email to the false
+
+143
+00:11:46,000 --> 00:11:47,000
+address?
+
+144
+00:11:47,000 --> 00:11:54,000
+Well, the see what problems may appear to address all issues mentioned above.
+
+145
+00:11:54,000 --> 00:11:56,000
+You can just use surrogate key.
+
+146
+00:11:57,000 --> 00:12:04,000
+On the contrary to natural case surrogates, kid doesn't have a natural relationship with the rest data
+
+147
+00:12:04,000 --> 00:12:05,000
+in the record.
+
+148
+00:12:05,000 --> 00:12:13,000
+That's why, no matter how records will change, your surrogate key will stay the same because its only
+
+149
+00:12:13,000 --> 00:12:17,000
+goal is to identify records in the table.
+
+150
+00:12:17,000 --> 00:12:19,000
+That's it, and nothing more.
+
+151
+00:12:20,000 --> 00:12:27,000
+Usually, this is integer value that is incremented with each new row, and you are not Borsa at Wiscasset
+
+152
+00:12:27,000 --> 00:12:31,000
+in need or thinking about any false value.
+
+153
+00:12:31,000 --> 00:12:36,000
+I recommend it to use surrogate keys, but this will be only up to you.
+
+154
+00:12:36,000 --> 00:12:41,000
+Summarizing limbo, let's come up with advantages of surrogates.
+
+155
+00:12:41,000 --> 00:12:47,000
+Case surrogate Qi has no any business related information built in it.
+
+156
+00:12:47,000 --> 00:12:50,000
+This makes sinks easier.
+
+157
+00:12:50,000 --> 00:12:54,000
+We shouldn't worry about updating it in all related tables.
+
+158
+00:12:55,000 --> 00:13:01,000
+Performing cascading operations in case some business related information from primary key has been
+
+159
+00:13:01,000 --> 00:13:02,000
+changed.
+
+160
+00:13:02,000 --> 00:13:10,000
+Also, this type of case takes less memory because usually we use integer time for surrogate keys,
+
+161
+00:13:10,000 --> 00:13:12,000
+and this is only four bytes.
+
+162
+00:13:12,000 --> 00:13:17,000
+Usually, requests on different tables also completed faster.
+
+163
+00:13:17,000 --> 00:13:23,000
+Usually, there are no reasons to change surrogate qi because it is just and then the fire.
+
+164
+00:13:24,000 --> 00:13:29,000
+Thus, there is no need in cascading need of the value in all related tables.
+
+165
+00:13:30,000 --> 00:13:37,000
+And the only drawback is that I see in using surrogate integer key is that it can limit the number of
+
+166
+00:13:37,000 --> 00:13:43,000
+rows in the table because at the end of the day, we have limited amount of memory reserved for data
+
+167
+00:13:43,000 --> 00:13:47,000
+of integer type that is four bytes only.
+
+168
+00:13:47,000 --> 00:13:52,000
+But on the other hand, you can use unsigned integer value.
+
+169
+00:13:53,000 --> 00:13:59,000
+This gives you opportunity to use one low need to store additional information, and in total, you
+
+170
+00:13:59,000 --> 00:14:02,000
+can create more than four billion the rules.
+
+171
+00:14:03,000 --> 00:14:08,000
+And believe me, if you have more than four million records in your table, you're going to have a lot
+
+172
+00:14:08,000 --> 00:14:11,000
+of other problems besides limit of integer value.
+
+173
+00:14:12,000 --> 00:14:18,000
+And if you have four billion users registered in your app, you have enough resources to apply workarounds
+
+174
+00:14:18,000 --> 00:14:18,000
+for this issue.
+
+175
+00:14:19,000 --> 00:14:24,000
+One was a solution, maybe is to create table was big and start for primary care.
+
+176
+00:14:25,000 --> 00:14:30,000
+This data type use eight bytes to store information, which should be enough.
+
+177
+00:14:31,000 --> 00:14:37,000
+And after that, you can copy and paste rows from one table to another and update the last tidy value
+
+178
+00:14:37,000 --> 00:14:42,000
+for all the increment in order you can proceed, adding new ideas for new records.
+
+179
+00:14:43,000 --> 00:14:48,000
+Don't worry, I'm going to show you how to do this on practice in the following lessons.
+
+180
+00:14:49,000 --> 00:14:54,000
+We already know what's primary case and learned different classifications of primary case.
+
+181
+00:14:55,000 --> 00:15:04,000
+Now let me explain what alternate care is there also called sometimes secondary case alternate case
+
+182
+00:15:04,000 --> 00:15:11,000
+as those candidates case, which are not the primary care since there's only one primary care for a
+
+183
+00:15:11,000 --> 00:15:11,000
+table.
+
+184
+00:15:11,000 --> 00:15:19,000
+Other fields that are also unique and can be used for Typekit identification are called alternate case.
+
+185
+00:15:19,000 --> 00:15:25,000
+For example, imagine that you have table was users and you decided to use surrogate primary care,
+
+186
+00:15:25,000 --> 00:15:29,000
+but you also have another column that contains only unique values.
+
+187
+00:15:30,000 --> 00:15:33,000
+It can be common with emails, for example.
+
+188
+00:15:33,000 --> 00:15:38,000
+Indeed, it is impossible that users will have the same email the system.
+
+189
+00:15:39,000 --> 00:15:43,000
+But database administrator decided to use it as a primary key.
+
+190
+00:15:44,000 --> 00:15:51,000
+We unique restriction to a mail column and still can use it to extract user when needed.
+
+191
+00:15:51,000 --> 00:15:55,000
+But this attribute may be considered as an alternate care.
+
+192
+00:15:55,000 --> 00:15:56,000
+Is that clear?
+
+193
+00:15:57,000 --> 00:15:59,000
+Now let's look at another important term.
+
+194
+00:15:59,000 --> 00:16:02,000
+Let me explain what foreign key is.
+
+195
+00:16:02,000 --> 00:16:09,000
+One key is an attribute which is primary key in its parent table, but is included as an action.
+
+196
+00:16:09,000 --> 00:16:16,000
+But in another table with the goal to establish connection between entities, we already know that in
+
+197
+00:16:16,000 --> 00:16:24,000
+relational database we may have different tables and tables will be connected with each other to avoid
+
+198
+00:16:24,000 --> 00:16:30,000
+data duplication and to ensure the most efficient and consistent data storage neutrally.
+
+199
+00:16:30,000 --> 00:16:36,000
+In the minute, you're going to see examples how relationships between different tables are established.
+
+200
+00:16:37,000 --> 00:16:40,000
+So now you know what primary key and foreign key is.
+
+201
+00:16:41,000 --> 00:16:47,000
+That means we can learn type of relationships and understand technical side of establishing connections
+
+202
+00:16:47,000 --> 00:16:48,000
+between tables.
+
+203
+00:16:49,000 --> 00:16:52,000
+First of all, let's understand what relationship is.
+
+204
+00:16:53,000 --> 00:17:00,000
+There is a definition from a relational database theory that was defined by Edgar Frankel, inventor
+
+205
+00:17:00,000 --> 00:17:03,000
+of relational model database management.
+
+206
+00:17:03,000 --> 00:17:09,000
+But instead of reading that definition, I'm going to explain you what relationship is, in simple words,
+
+207
+00:17:10,000 --> 00:17:16,000
+relationship in a relational database management system using an association of records from two or
+
+208
+00:17:16,000 --> 00:17:17,000
+more tables.
+
+209
+00:17:18,000 --> 00:17:23,000
+Let me also explain the relationship on example from real life user has a car.
+
+210
+00:17:24,000 --> 00:17:30,000
+This is a relationship between the user of the car and dependent on the number of objects from each
+
+211
+00:17:30,000 --> 00:17:31,000
+side of this relationship.
+
+212
+00:17:32,000 --> 00:17:35,000
+Then different types of relationship is that clear.
+
+213
+00:17:36,000 --> 00:17:39,000
+In the relational database, there are three types of relationships.
+
+214
+00:17:40,000 --> 00:17:42,000
+They are one to many.
+
+215
+00:17:43,000 --> 00:17:48,000
+That is when one user math many cars matter to many.
+
+216
+00:17:48,000 --> 00:17:57,000
+One user may have a lot of cars and one car may be owned by two users, by two co-owners and one to
+
+217
+00:17:57,000 --> 00:17:58,000
+one.
+
+218
+00:17:58,000 --> 00:18:03,000
+This relationship one one user can own one car only.
+
+219
+00:18:04,000 --> 00:18:10,000
+And now I'd like you to understand each of these relationship types, one by one in details, we'll
+
+220
+00:18:10,000 --> 00:18:13,000
+try to understand that logical first.
+
+221
+00:18:13,000 --> 00:18:20,000
+And after that, I will provide technical explanation on how this is implemented on database level one
+
+222
+00:18:20,000 --> 00:18:27,000
+to many means that one object from one table may be related to many objects from another table.
+
+223
+00:18:28,000 --> 00:18:31,000
+Now, a particular example was user and car.
+
+224
+00:18:31,000 --> 00:18:34,000
+We can apply want the money relationship in the next week?
+
+225
+00:18:34,000 --> 00:18:40,000
+One user may own multiple cars, but each car has only one user.
+
+226
+00:18:41,000 --> 00:18:43,000
+This is equal to one to many relationship.
+
+227
+00:18:44,000 --> 00:18:46,000
+One user owning many cars.
+
+228
+00:18:46,000 --> 00:18:47,000
+Does it make sense?
+
+229
+00:18:48,000 --> 00:18:53,000
+If you understood it logically, let's learn how this is implemented on database level.
+
+230
+00:18:54,000 --> 00:19:01,000
+Each relationship is implemented by migration of primary care from parent table in the direction of
+
+231
+00:19:01,000 --> 00:19:01,000
+another table.
+
+232
+00:19:02,000 --> 00:19:07,000
+The fields that we received after this migration is called foreign key.
+
+233
+00:19:08,000 --> 00:19:11,000
+In this example, we have table user and table car.
+
+234
+00:19:12,000 --> 00:19:16,000
+We add new column and table car that is called user I.D..
+
+235
+00:19:17,000 --> 00:19:23,000
+This will be a column as a source for Enki and for each car of specific user.
+
+236
+00:19:24,000 --> 00:19:29,000
+We pulled his I.D. and that's it was successfully established relationship.
+
+237
+00:19:30,000 --> 00:19:33,000
+Now you can query these two tables together.
+
+238
+00:19:33,000 --> 00:19:42,000
+For example, your query may sound like this return we can manufacture of each car that belongs to the
+
+239
+00:19:42,000 --> 00:19:50,000
+user was a new one and user email, and you have enough information to map records from two tables between
+
+240
+00:19:50,000 --> 00:19:51,000
+each other.
+
+241
+00:19:52,000 --> 00:19:53,000
+Do you understand?
+
+242
+00:19:54,000 --> 00:20:00,000
+In our sequel lesson, I will teach you how to grade school queries to retrieve this kind of information.
+
+243
+00:20:01,000 --> 00:20:03,000
+But is it clear for you, at least on the high level?
+
+244
+00:20:04,000 --> 00:20:11,000
+Remember, understanding the concept is much more important rather than understanding of detailed query,
+
+245
+00:20:11,000 --> 00:20:18,000
+because syntax of sequel is something you can always learn and something what you can always find on
+
+246
+00:20:18,000 --> 00:20:19,000
+the internet.
+
+247
+00:20:19,000 --> 00:20:27,000
+But deep understanding this assumption was belongs only to you and can be found in the internet.
+
+248
+00:20:27,000 --> 00:20:34,000
+So I suppose for a minute, if needed to understand this, once you feel sure that you understood this.
+
+249
+00:20:34,000 --> 00:20:35,000
+Let's proceed.
+
+250
+00:20:36,000 --> 00:20:43,000
+On the dining room, we usually mark this relationship with asterisk and one digit asterisk stands for
+
+251
+00:20:43,000 --> 00:20:44,000
+many.
+
+252
+00:20:44,000 --> 00:20:46,000
+And one stands for one.
+
+253
+00:20:47,000 --> 00:20:50,000
+Again, one user and many cars.
+
+254
+00:20:50,000 --> 00:20:52,000
+Each car has only one user.
+
+255
+00:20:53,000 --> 00:21:00,000
+One more thing in case you are going to use object, relational map and framework in your programming
+
+256
+00:21:00,000 --> 00:21:06,000
+language, you may find that sometimes there is a difference between one to many and many to one relationship.
+
+257
+00:21:07,000 --> 00:21:15,000
+Basically, these are the same relationship types, but the difference in what is read here in the current
+
+258
+00:21:15,000 --> 00:21:22,000
+object between the related other objects, for example, in the same case, relationship will be named
+
+259
+00:21:22,000 --> 00:21:30,000
+one to many in the user entity, and it will be managed to one incur entity do feel the difference.
+
+260
+00:21:31,000 --> 00:21:31,000
+That's great.
+
+261
+00:21:32,000 --> 00:21:32,000
+Let's move on.
+
+262
+00:21:34,000 --> 00:21:40,000
+And the next relationship that we are going to review today is managed to manage this kind of relationship
+
+263
+00:21:40,000 --> 00:21:47,000
+defiance as a situation when one records from one table may be connected to as many records from another
+
+264
+00:21:47,000 --> 00:21:52,000
+table and one records from another table may be connected to as many records from the first table.
+
+265
+00:21:53,000 --> 00:21:56,000
+I can say that many to many relationship.
+
+266
+00:21:56,000 --> 00:22:02,000
+It is also humans name, and technically this is just too one.
+
+267
+00:22:02,000 --> 00:22:07,000
+Too many relationships implemented in two directions doesn't make sense.
+
+268
+00:22:08,000 --> 00:22:11,000
+Let's try to understand how to implement this.
+
+269
+00:22:11,000 --> 00:22:14,000
+Imagine that we have students and different courses.
+
+270
+00:22:15,000 --> 00:22:22,000
+Each student may enroll in multiple courses, and basically each course may ask multiple students.
+
+271
+00:22:22,000 --> 00:22:30,000
+We have bidirectional one to many relationship between these two tables or, in other words, many too
+
+272
+00:22:30,000 --> 00:22:31,000
+many.
+
+273
+00:22:31,000 --> 00:22:39,000
+In this case, we can't just put foreign key into tables because we need to build many relationships
+
+274
+00:22:39,000 --> 00:22:45,000
+on one side and many relationships for each record on another side.
+
+275
+00:22:45,000 --> 00:22:50,000
+So technically, this is impossible to do with two tables only.
+
+276
+00:22:51,000 --> 00:22:56,000
+That's why to organize money into money relationships between two tables when it degrades a set table.
+
+277
+00:22:57,000 --> 00:23:05,000
+This table will contain foreign keys from one and the second tables and will map them between each other.
+
+278
+00:23:06,000 --> 00:23:13,000
+In this particular case, each student was I.D. one in the world, and some course we map these, of
+
+279
+00:23:13,000 --> 00:23:16,000
+course, and student in the SEC table.
+
+280
+00:23:16,000 --> 00:23:21,000
+And even this course has also students was I need to hand suite.
+
+281
+00:23:21,000 --> 00:23:25,000
+We also specify this in the table here.
+
+282
+00:23:25,000 --> 00:23:31,000
+We have Compound's primary key combination of these two fields has to be unique in each step.
+
+283
+00:23:32,000 --> 00:23:38,000
+Regarding naming convention for such tables, it depends on the final purpose of this table.
+
+284
+00:23:38,000 --> 00:23:45,000
+If we just want to establish connection between two entities, then we can use and the two names and
+
+285
+00:23:45,000 --> 00:23:48,000
+the verb that describes connection between them.
+
+286
+00:23:48,000 --> 00:23:56,000
+In this case, we can names a stable student has course or even should a student course, in case we
+
+287
+00:23:56,000 --> 00:24:04,000
+would add another business related info in each sample like date of enrollment, price information about
+
+288
+00:24:04,000 --> 00:24:09,000
+discounts and in case we're going to operate with this entity, as was a separate one.
+
+289
+00:24:10,000 --> 00:24:17,000
+In this case, we can give some business variable name to this table, for example, enrollment is that
+
+290
+00:24:17,000 --> 00:24:18,000
+clear.
+
+291
+00:24:19,000 --> 00:24:22,000
+And we have one more type of relationship to discuss.
+
+292
+00:24:23,000 --> 00:24:25,000
+I'm talking about one to one relationship.
+
+293
+00:24:25,000 --> 00:24:29,000
+This is the rarest type of relationship, to be honest.
+
+294
+00:24:29,000 --> 00:24:36,000
+Based on my experience, you would face was one too many and many, too many relationships more often
+
+295
+00:24:36,000 --> 00:24:38,000
+than was one to one.
+
+296
+00:24:38,000 --> 00:24:45,000
+Because this type of relationship describes very specific business case one one records in one table
+
+297
+00:24:45,000 --> 00:24:49,000
+is related with only one record from another table.
+
+298
+00:24:49,000 --> 00:24:52,000
+Can you think of cases like this?
+
+299
+00:24:52,000 --> 00:24:53,000
+It is hard to do.
+
+300
+00:24:53,000 --> 00:24:54,000
+Is that preparation?
+
+301
+00:24:55,000 --> 00:24:56,000
+And I can understand you.
+
+302
+00:24:57,000 --> 00:25:00,000
+I come up with some example for this type of relationship.
+
+303
+00:25:01,000 --> 00:25:06,000
+Imagine one transaction and you have table was all transactions in that.
+
+304
+00:25:07,000 --> 00:25:09,000
+And also there is transaction info table.
+
+305
+00:25:10,000 --> 00:25:13,000
+There is more detailed information about each transaction.
+
+306
+00:25:13,000 --> 00:25:19,000
+And it also stores sensitive information, and not all the users can read it.
+
+307
+00:25:19,000 --> 00:25:25,000
+That's why there is a need to store some attributes and values in secure table.
+
+308
+00:25:26,000 --> 00:25:32,000
+But still, there is a connection between these two tables, and each transaction is connected with
+
+309
+00:25:32,000 --> 00:25:36,000
+only one recording transaction in a table and vice versa.
+
+310
+00:25:37,000 --> 00:25:42,000
+Each transaction infrared connected to only one transaction.
+
+311
+00:25:42,000 --> 00:25:48,000
+To implement this connection, you can use two strategies you can use a use share key.
+
+312
+00:25:48,000 --> 00:25:56,000
+That means that the primary key in one table is equal to primary key in another table, or you can create
+
+313
+00:25:56,000 --> 00:26:02,000
+joint column and declare field where primary key will be exported in the table.
+
+314
+00:26:03,000 --> 00:26:09,000
+Most options are good in this case because they allow you to build the relationship between two tables.
+
+315
+00:26:10,000 --> 00:26:18,000
+I would just put a stress one more time on the fact that so many cases for one to one relationship heaven,
+
+316
+00:26:18,000 --> 00:26:24,000
+one to one relationship without clear argumentation is an indicator of pure database design.
+
+317
+00:26:25,000 --> 00:26:28,000
+That's all what I wanted to share with you in this lesson.
+
+318
+00:26:29,000 --> 00:26:36,000
+Now let's recap what we have learned today in this lesson of the grant basic terms in the relational
+
+319
+00:26:36,000 --> 00:26:37,000
+databases.
+
+320
+00:26:37,000 --> 00:26:43,000
+Now, you know the difference between such terms as database and schema you used in details of what
+
+321
+00:26:43,000 --> 00:26:45,000
+primary care is.
+
+322
+00:26:45,000 --> 00:26:52,000
+Also, we have learned different classifications of primary keys, such as single and compound, natural
+
+323
+00:26:52,000 --> 00:26:53,000
+and surrogate.
+
+324
+00:26:54,000 --> 00:26:59,000
+I explained to you what Ultimate Kit is after that.
+
+325
+00:26:59,000 --> 00:27:03,000
+We learned such an important concept in relational database as foreign key.
+
+326
+00:27:04,000 --> 00:27:08,000
+And at the end of the lesson, we've got three main types of relationship.
+
+327
+00:27:09,000 --> 00:27:15,000
+Now, you know the difference between one of the many, many too many and one to one relationships.
+
+328
+00:27:16,000 --> 00:27:17,000
+Thanks a lot for your attention, team.
+
+329
+00:27:18,000 --> 00:27:19,000
+Have a great day.
+
+330
+00:27:19,000 --> 00:27:20,000
+See you in the next lesson.
+

47 - Relational databases/002 Create Schema & Table Naming, Collation, Engines, Types, Column Properties_en.srt

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+1
+00:00:06,000 --> 00:00:07,000
+Hello came by this moment.
+
+2
+00:00:07,000 --> 00:00:12,000
+Now, of course, you already have some surgical knowledge about the relational databases.
+
+3
+00:00:12,000 --> 00:00:16,000
+And in this lesson, we're going to have more practice activities.
+
+4
+00:00:17,000 --> 00:00:22,000
+This lesson will be dedicated to learning of basic operations with database management system.
+
+5
+00:00:23,000 --> 00:00:26,000
+We are going to create schema and table in database.
+
+6
+00:00:26,000 --> 00:00:30,000
+And as we go, we'll learn a lot of interest in sinks.
+
+7
+00:00:31,000 --> 00:00:36,000
+We're going to have super interesting lessons because we'll start from practice activities.
+
+8
+00:00:36,000 --> 00:00:41,000
+And we're going to learn just enough series to achieve all of the lessons learned.
+
+9
+00:00:41,000 --> 00:00:44,000
+The lesson will perform operations in my school workbench.
+
+10
+00:00:44,000 --> 00:00:48,000
+And you will gradually start learning it step by step.
+
+11
+00:00:48,000 --> 00:00:54,000
+I would explain you what main buttons are and that will hold a live demo was explaining off each step
+
+12
+00:00:54,000 --> 00:00:55,000
+that I'm doing.
+
+13
+00:00:56,000 --> 00:01:02,000
+The main goal of the course in general and this lesson in particular, is orientation on skills that
+
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+you would need on practice and you already know enough theory to proceed with this lesson.
+
+15
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+If you watched all previous lessons, now will not have one more serious lesson because I understand
+
+16
+00:01:15,000 --> 00:01:21,000
+that it will be hard to remember so much information without understanding how this information may
+
+17
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+help you.
+
+18
+00:01:22,000 --> 00:01:25,000
+And why do you need to know it at all?
+
+19
+00:01:26,000 --> 00:01:31,000
+That's why in this lesson, we'll just create a schema and one table with you.
+
+20
+00:01:31,000 --> 00:01:37,000
+That's it sounds like not a lot of things to do, but still a lot of things to understand.
+
+21
+00:01:37,000 --> 00:01:40,000
+I will put separate focus on naming convention.
+
+22
+00:01:40,000 --> 00:01:43,000
+We'll talk about charset and collation.
+
+23
+00:01:43,000 --> 00:01:46,000
+Also, we are going to review my SQL storage engines.
+
+24
+00:01:47,000 --> 00:01:49,000
+One will start create columns in our table.
+
+25
+00:01:49,000 --> 00:01:53,000
+You will need to understand different data types and column properties.
+
+26
+00:01:54,000 --> 00:01:55,000
+Be prepared.
+
+27
+00:01:55,000 --> 00:01:58,000
+This is going to be interesting and useful lesson.
+
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+Let's start.
+
+29
+00:02:00,000 --> 00:02:02,000
+Let me start from the screen sharing straightaway.
+
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+00:02:03,000 --> 00:02:08,000
+As I already said, they were going to have a lot of practice activities in this lesson.
+
+31
+00:02:08,000 --> 00:02:10,000
+We're going to work in my school workbench.
+
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+In case you don't have neither my skill nor workbench installed, please refer to the previous lessons.
+
+33
+00:02:18,000 --> 00:02:24,000
+I have separate lesson where I explained how to install my school apps on your computer and configure
+
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+connection to my SQL server.
+
+35
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+So here is how our connected server looks like we are my SQL workbench, he writes about interface once
+
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+connections within my SQL server is established.
+
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+00:02:37,000 --> 00:02:39,000
+You have a separate topic here.
+
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+You can return back on the home page if you wish.
+
+39
+00:02:43,000 --> 00:02:49,000
+By clicking on this icon and vice versa menu options are located here on top.
+
+40
+00:02:50,000 --> 00:02:54,000
+One of the most frequently used operations depicted, we are icons here.
+
+41
+00:02:55,000 --> 00:02:56,000
+We're going to use them and learn.
+
+42
+00:02:56,000 --> 00:02:58,000
+During the work was workbench.
+
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+00:02:58,000 --> 00:03:07,000
+Some of them are great SQL query, tap, create schema, create table inactive database, create a new
+
+44
+00:03:07,000 --> 00:03:09,000
+view and others.
+
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+00:03:09,000 --> 00:03:16,000
+Gradually, we'll have practice with each of these options potentially set in navigator view.
+
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+00:03:16,000 --> 00:03:20,000
+You have two taps, layer administration and schemas.
+
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+00:03:21,000 --> 00:03:27,000
+Since this is our first practical lesson, I wouldn't start from administration tab because I believe
+
+48
+00:03:27,000 --> 00:03:30,000
+we need to start from something more simple in this moment.
+
+49
+00:03:31,000 --> 00:03:37,000
+We're going to have also a separate lesson where I will explain how the administrator database, including
+
+50
+00:03:37,000 --> 00:03:43,000
+data imports and exports users and privileges configuration, server performance monitoring and others.
+
+51
+00:03:44,000 --> 00:03:51,000
+So in this lesson, let's perform our first steps in order to create our database and fill it out with
+
+52
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+data.
+
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+00:03:52,000 --> 00:03:55,000
+The first thing that we need to do is to create schema.
+
+54
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+Find this, I can hear it will help us to create schema.
+
+55
+00:04:00,000 --> 00:04:03,000
+We need to specify name of our schema.
+
+56
+00:04:03,000 --> 00:04:08,000
+Let's call it learning TDB and the first rule here.
+
+57
+00:04:08,000 --> 00:04:14,000
+While this is not a strict rule and you will grigg's a database, it is still strongly recommended to
+
+58
+00:04:14,000 --> 00:04:20,000
+follow the naming convention and naming convention is a set of unwritten rules.
+
+59
+00:04:20,000 --> 00:04:27,000
+We all should use if you want an increase in the ability of the whole data model will apply these rules
+
+60
+00:04:27,000 --> 00:04:35,000
+while naming A.I. inside the database tables, columns, primary and foreign keys, stored procedures,
+
+61
+00:04:35,000 --> 00:04:43,000
+functions, views, etc. While most rules are pretty logical, you could go with some you have invented
+
+62
+00:04:43,000 --> 00:04:45,000
+and that is completely up to you.
+
+63
+00:04:45,000 --> 00:04:52,000
+For example, when name any data be subject, it is recommended to use lower letters in case when you
+
+64
+00:04:52,000 --> 00:04:54,000
+to have multiple words and name.
+
+65
+00:04:54,000 --> 00:05:00,000
+We use underscore like in this case, for example, learn, underscore key.
+
+66
+00:05:00,000 --> 00:05:02,000
+Underscore me is a clear.
+
+67
+00:05:03,000 --> 00:05:10,000
+I believe that it is clear for you how to use Underscores, but probably the only one things that are
+
+68
+00:05:10,000 --> 00:05:16,000
+still not clear for you is why we need to follow naming convention and what benefits we expect to get.
+
+69
+00:05:16,000 --> 00:05:23,000
+For example, why we just can't follow the same naming convention as we have in Java and use camel case.
+
+70
+00:05:24,000 --> 00:05:27,000
+Let me name a few reasons to follow naming convention.
+
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+00:05:28,000 --> 00:05:28,000
+Reason number one.
+
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+Simplicity of the base model.
+
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+Usually, you don't have just one or two tables in your database.
+
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+00:05:36,000 --> 00:05:42,000
+Users are much more of them in your database, and having consistent naming would simplify navigation
+
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+00:05:42,000 --> 00:05:44,000
+between the tables and data.
+
+76
+00:05:44,000 --> 00:05:49,000
+Because to avoid total mass, you have to follow up this summer organizational rules.
+
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+00:05:49,000 --> 00:05:52,000
+The second reason is database stability.
+
+78
+00:05:52,000 --> 00:05:58,000
+If you decided to use the same naming convention as a programming language of your application, you
+
+79
+00:05:58,000 --> 00:06:04,000
+have to remember one more rule usually that the base is one of the most stable components in your app.
+
+80
+00:06:05,000 --> 00:06:09,000
+Changes and database layer one and only done with it is necessary.
+
+81
+00:06:10,000 --> 00:06:16,000
+Imagine that you would like to use Java naming convention for a database, but in one year you decided
+
+82
+00:06:16,000 --> 00:06:24,000
+to have other modules or even on loads of vital each, and those modules also interact with this database.
+
+83
+00:06:25,000 --> 00:06:26,000
+What will you do?
+
+84
+00:06:26,000 --> 00:06:33,000
+You can constantly change naming convention just because you changed main programming language in your
+
+85
+00:06:33,000 --> 00:06:35,000
+app that understands this.
+
+86
+00:06:36,000 --> 00:06:42,000
+In case you follow database naming convention, you can expect that even after you change the programming
+
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+language of your app, you still have stable database there.
+
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+This will help you to keep your database well, organized and structured.
+
+89
+00:06:52,000 --> 00:06:57,000
+And the last, but not the least reason with the ability of data monitoring by each team member.
+
+90
+00:06:57,000 --> 00:07:03,000
+Once you have specific paths that you follow, it will be easier for you and what is also important?
+
+91
+00:07:03,000 --> 00:07:07,000
+It would be easier for colleagues of yours to query a database.
+
+92
+00:07:07,000 --> 00:07:15,000
+What it often work Broken teams no small or big, and very often with support databases created not
+
+93
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+by us.
+
+94
+00:07:16,000 --> 00:07:20,000
+That's why following common rules would simplify our lives.
+
+95
+00:07:21,000 --> 00:07:21,000
+Is that clear?
+
+96
+00:07:22,000 --> 00:07:28,000
+Even in case you still have any questions, please put your questions below this video, and I will
+
+97
+00:07:28,000 --> 00:07:30,000
+be happy to answer those.
+
+98
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+So we specified name for our new schema.
+
+99
+00:07:34,000 --> 00:07:36,000
+What else we need to specify here?
+
+100
+00:07:36,000 --> 00:07:41,000
+Let's check together the next thing that we need to specify here.
+
+101
+00:07:41,000 --> 00:07:43,000
+I charset and collation.
+
+102
+00:07:43,000 --> 00:07:47,000
+Let's have you one by one and we'll start from Charset first.
+
+103
+00:07:48,000 --> 00:07:53,000
+And my second character set is a set of characters that are legal in a string.
+
+104
+00:07:53,000 --> 00:08:00,000
+For example, imagine that we have English alphabet from A to Z, and then we assign each letter to
+
+105
+00:08:00,000 --> 00:08:00,000
+a number.
+
+106
+00:08:00,000 --> 00:08:04,000
+We have a equal to one be equal to do and so on.
+
+107
+00:08:05,000 --> 00:08:07,000
+In this case, a is a symbol.
+
+108
+00:08:08,000 --> 00:08:15,000
+And number one that is associated with the letter A is encoded is a combination of all letters from
+
+109
+00:08:15,000 --> 00:08:20,000
+A to Z and Zach responding in accordance is a character set.
+
+110
+00:08:20,000 --> 00:08:21,000
+This makes sense.
+
+111
+00:08:22,000 --> 00:08:25,000
+Can you understand now what the charset is?
+
+112
+00:08:25,000 --> 00:08:30,000
+Let's select in charset UTF eight and B for?
+
+113
+00:08:31,000 --> 00:08:37,000
+Because we need Typekit UTF eight and coding sets use for bytes to store character.
+
+114
+00:08:37,000 --> 00:08:46,000
+By default, most people use UTF eight as Alice off UTF eight and B three is its only source and maximum
+
+115
+00:08:46,000 --> 00:08:48,000
+of three bytes per quarter point.
+
+116
+00:08:49,000 --> 00:08:54,000
+On the official website of my school, it is referred as deprecated and it is mentioned that it will
+
+117
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+be removed.
+
+118
+00:08:55,000 --> 00:09:03,000
+Instead, it is recommended to use UTF eight and B for each character set has one or more correlations.
+
+119
+00:09:03,000 --> 00:09:04,000
+Is it defined?
+
+120
+00:09:04,000 --> 00:09:10,000
+A set of rules for comparing characters within the character set and my school collation is a set of
+
+121
+00:09:10,000 --> 00:09:14,000
+rules used to compare characters in the particular character.
+
+122
+00:09:14,000 --> 00:09:21,000
+Set each character set in my school as at least one default collation, and it can have more than one
+
+123
+00:09:21,000 --> 00:09:22,000
+collation.
+
+124
+00:09:23,000 --> 00:09:29,000
+However, the character sets cannot have the same collation, usually as there is a default collation
+
+125
+00:09:29,000 --> 00:09:32,000
+associated with each other set.
+
+126
+00:09:32,000 --> 00:09:39,000
+But during the creation of our schema, we can select a collation for our charset by convention.
+
+127
+00:09:40,000 --> 00:09:45,000
+Collation for a current set begins with the character, set name and ends with.
+
+128
+00:09:46,000 --> 00:09:55,000
+As I just stands for case insensitive, CSA stands for case sensitive or being as it stands for binary.
+
+129
+00:09:56,000 --> 00:10:04,000
+My school allows you to specify a character set and collation at levels server, database, table and
+
+130
+00:10:04,000 --> 00:10:04,000
+column.
+
+131
+00:10:05,000 --> 00:10:11,000
+Currently, we can set up collation and database level, and if you are wondering which collation to
+
+132
+00:10:11,000 --> 00:10:19,000
+choose, I recommend you to go with UTF rmv for Unicode psi so that sorting is always handled properly.
+
+133
+00:10:19,000 --> 00:10:22,000
+It was minimal and noticeable performance drawbacks.
+
+134
+00:10:23,000 --> 00:10:29,000
+Anyway, you can see there are really a lot of different variations of collation here, and you can
+
+135
+00:10:29,000 --> 00:10:35,000
+check documentation to select the ones that works best for you in case you're also experiencing issues.
+
+136
+00:10:35,000 --> 00:10:41,000
+Was interface here like I do, and you can see the whole name of just selection.
+
+137
+00:10:41,000 --> 00:10:42,000
+Don't worry.
+
+138
+00:10:42,000 --> 00:10:48,000
+In my school revenge area operations that you are going to perform, this translates into SQL quick
+
+139
+00:10:49,000 --> 00:10:52,000
+and you can check query before execution of any command.
+
+140
+00:10:53,000 --> 00:10:57,000
+By the way, this is also one of the ways to learn sequel better.
+
+141
+00:10:58,000 --> 00:11:02,000
+I click a plain button here and here you can see SQL query.
+
+142
+00:11:02,000 --> 00:11:04,000
+This is not the lesson about a sequel.
+
+143
+00:11:05,000 --> 00:11:11,000
+My goal was to let you understand what operations we need and we can do in general.
+
+144
+00:11:11,000 --> 00:11:15,000
+Our database and only after that jump to none in the sequel.
+
+145
+00:11:15,000 --> 00:11:20,000
+Because when I started learning SQL School with students straight away, they just couldn't understand
+
+146
+00:11:20,000 --> 00:11:23,000
+why they need this and what they're doing with it.
+
+147
+00:11:24,000 --> 00:11:31,000
+As you can see here, we use great operator to create schema with name 90 DB with default character
+
+148
+00:11:31,000 --> 00:11:36,000
+set UTF eight and before and collation UTF eight and before in the courtyard.
+
+149
+00:11:37,000 --> 00:11:44,000
+Even in case you select the wrong option because you were not able to use a full name and drop down.
+
+150
+00:11:45,000 --> 00:11:47,000
+You can adjust name of collation here.
+
+151
+00:11:48,000 --> 00:11:50,000
+Now, query looks good to me.
+
+152
+00:11:50,000 --> 00:11:51,000
+That's executed.
+
+153
+00:11:52,000 --> 00:11:58,000
+In case operation was successful, you can see a sequel statement has been executed successfully.
+
+154
+00:11:58,000 --> 00:12:03,000
+Click Finish Button now on Sikkema Step on the left.
+
+155
+00:12:03,000 --> 00:12:06,000
+We can see that we have a new schema in the list here.
+
+156
+00:12:07,000 --> 00:12:13,000
+Nemo Creek was mouse left click and once the name of the database is in bold, that means you selected
+
+157
+00:12:13,000 --> 00:12:16,000
+the specific database and you can work with it.
+
+158
+00:12:17,000 --> 00:12:22,000
+Inside, you can see that we may have tables, views, stored procedures, functions.
+
+159
+00:12:23,000 --> 00:12:28,000
+We are going to learn how to create all these database objects and how to work with them.
+
+160
+00:12:28,000 --> 00:12:33,000
+But in this lesson, let's create table and perform basic operations with it.
+
+161
+00:12:34,000 --> 00:12:38,000
+We can create table people using the workbench interface in different ways.
+
+162
+00:12:38,000 --> 00:12:45,000
+You can use one of the many items here is at the school to create new table or you can use menu.
+
+163
+00:12:46,000 --> 00:12:50,000
+I do mouse right click on tables and select Create Table.
+
+164
+00:12:51,000 --> 00:12:54,000
+Let me walk you through the configuration here.
+
+165
+00:12:55,000 --> 00:12:59,000
+The first thing we need to specify here is stable name.
+
+166
+00:12:59,000 --> 00:13:06,000
+Let's imagine that we want to create user table user table will contain information about users.
+
+167
+00:13:06,000 --> 00:13:10,000
+And now we're in sync about naming convention for tables.
+
+168
+00:13:11,000 --> 00:13:17,000
+One of the arguable questions is whether you need to use plural and the naming of tables or singular.
+
+169
+00:13:17,000 --> 00:13:24,000
+For example, if you're going to store users in this table, isn't it logical to name table users in
+
+170
+00:13:24,000 --> 00:13:24,000
+plural?
+
+171
+00:13:25,000 --> 00:13:27,000
+So different points of view on this?
+
+172
+00:13:28,000 --> 00:13:28,000
+Let me explain.
+
+173
+00:13:30,000 --> 00:13:33,000
+The first option is to use Singapore four table name.
+
+174
+00:13:33,000 --> 00:13:35,000
+That is what I would recommend you to.
+
+175
+00:13:36,000 --> 00:13:41,000
+I prefer to use the uninfected noun, which in English happens to be singular.
+
+176
+00:13:42,000 --> 00:13:48,000
+If your name and entities that represent real world facts, you should use nouns.
+
+177
+00:13:49,000 --> 00:13:54,000
+These are tables like employee, customer, city and country, for example.
+
+178
+00:13:55,000 --> 00:14:00,000
+If possible, use a single word that exactly describes what is in the table.
+
+179
+00:14:01,000 --> 00:14:05,000
+Let's try to understand what benefits this brings to us.
+
+180
+00:14:05,000 --> 00:14:12,000
+The first reason is logical and semantic, and really understands that this is also maybe considered
+
+181
+00:14:12,000 --> 00:14:13,000
+as arguable point.
+
+182
+00:14:14,000 --> 00:14:21,000
+For example, at your home, if you have back with socks, you would put a label on it that says sucks,
+
+183
+00:14:22,000 --> 00:14:24,000
+but not Sock and Single-A.
+
+184
+00:14:24,000 --> 00:14:29,000
+But another question why you should apply naming convention from socks to a database?
+
+185
+00:14:30,000 --> 00:14:30,000
+Just joking.
+
+186
+00:14:30,000 --> 00:14:37,000
+But indeed, naming people in plural form also contains some logical hosts, because if you want to
+
+187
+00:14:37,000 --> 00:14:42,000
+name people in plural, why would don't ask us questions about grammar too?
+
+188
+00:14:43,000 --> 00:14:49,000
+For example, we also might be thinking about questions like this, since we're usually doing something
+
+189
+00:14:49,000 --> 00:14:50,000
+with zeros.
+
+190
+00:14:50,000 --> 00:14:55,000
+Why not to put the name in the accusative case or another question?
+
+191
+00:14:55,000 --> 00:15:03,000
+If we have a tables that will write to laws and we agree, why not put the name indeed, if it is table
+
+192
+00:15:03,000 --> 00:15:04,000
+of Simpson?
+
+193
+00:15:04,000 --> 00:15:06,000
+Why not use genitive?
+
+194
+00:15:07,000 --> 00:15:07,000
+And you know what?
+
+195
+00:15:08,000 --> 00:15:12,000
+We will not constantly address all of these questions because we will end up with a mess.
+
+196
+00:15:13,000 --> 00:15:15,000
+The table is defined as an abstract.
+
+197
+00:15:15,000 --> 00:15:20,000
+Content exists regardless of its state or usage uses.
+
+198
+00:15:20,000 --> 00:15:26,000
+An unaffected noun is simple, logical, regular and language independent.
+
+199
+00:15:27,000 --> 00:15:28,000
+The second reason is convenience.
+
+200
+00:15:29,000 --> 00:15:32,000
+It is easy to come out with a single names.
+
+201
+00:15:32,000 --> 00:15:33,000
+Xen was plural.
+
+202
+00:15:33,000 --> 00:15:41,000
+Once objects can have irregular plurals, are not normal at all, but will always have a single one.
+
+203
+00:15:41,000 --> 00:15:43,000
+With few exceptions like news.
+
+204
+00:15:44,000 --> 00:15:46,000
+Another reason is simplicity.
+
+205
+00:15:46,000 --> 00:15:51,000
+One little gem to learn in the sequel, you are going to use table names for queries.
+
+206
+00:15:51,000 --> 00:15:58,000
+Also, we're going to refer to attributes of a table like, for example, to get the value of name attributes
+
+207
+00:15:58,000 --> 00:15:58,000
+and use.
+
+208
+00:15:58,000 --> 00:16:04,000
+Our table will use user not name, but not users, not name.
+
+209
+00:16:04,000 --> 00:16:07,000
+And it seems logical and simple.
+
+210
+00:16:07,000 --> 00:16:08,000
+Don't you think so?
+
+211
+00:16:08,000 --> 00:16:13,000
+You extract the name of specific user, but not all users.
+
+212
+00:16:14,000 --> 00:16:14,000
+Definitely.
+
+213
+00:16:14,000 --> 00:16:19,000
+I can find the workarounds for these two more experienced students.
+
+214
+00:16:19,000 --> 00:16:24,000
+While watching this video may mention that we can use Alliss for table names.
+
+215
+00:16:24,000 --> 00:16:26,000
+But why we need to do this?
+
+216
+00:16:26,000 --> 00:16:29,000
+You could just can name table in singular.
+
+217
+00:16:29,000 --> 00:16:29,000
+And that's it.
+
+218
+00:16:30,000 --> 00:16:35,000
+I'm the guy who always finds a way to simplify everything to the possible degree.
+
+219
+00:16:35,000 --> 00:16:37,000
+And this is one of the cases.
+
+220
+00:16:37,000 --> 00:16:43,000
+One more reason is that often consider it's not like an important one, but still it's worth of your
+
+221
+00:16:43,000 --> 00:16:43,000
+attention.
+
+222
+00:16:44,000 --> 00:16:45,000
+It is globalization.
+
+223
+00:16:45,000 --> 00:16:51,000
+We often work in multinational teams, and we're often for many of team members.
+
+224
+00:16:51,000 --> 00:16:58,000
+English is not native language and having a repository table instead of repositories or having status
+
+225
+00:16:58,000 --> 00:17:00,000
+table instead of statuses.
+
+226
+00:17:00,000 --> 00:17:07,000
+We'll save your team a lot of time and minimize errors because of typos and similar linguistic issues.
+
+227
+00:17:07,000 --> 00:17:13,000
+Probably this is not like the most critical reason to use single names for tables.
+
+228
+00:17:13,000 --> 00:17:15,000
+But promise me just to think about it.
+
+229
+00:17:16,000 --> 00:17:23,000
+And that's a point to think about, you know, the table names may consist of multiple words separated
+
+230
+00:17:23,000 --> 00:17:27,000
+by underscore this would raise additional questions from your team.
+
+231
+00:17:27,000 --> 00:17:30,000
+What words should be in plural and which not?
+
+232
+00:17:31,000 --> 00:17:37,000
+For example, or the detail if you use single zone, no questions at all.
+
+233
+00:17:37,000 --> 00:17:42,000
+It is simple to write queries because you remember that everything isn't singular.
+
+234
+00:17:43,000 --> 00:17:46,000
+But in case you would like to follow some grammar, how far will you go?
+
+235
+00:17:47,000 --> 00:17:54,000
+Really use all the details or some key members, many things that you should name this table as order
+
+236
+00:17:54,000 --> 00:17:55,000
+details.
+
+237
+00:17:55,000 --> 00:18:01,000
+Believe me, this might happen and this will happen in big multinational team, and they give you a
+
+238
+00:18:01,000 --> 00:18:05,000
+chance to think about it right now before you start that new project.
+
+239
+00:18:06,000 --> 00:18:10,000
+And always remember the tables are the subjects of the database.
+
+240
+00:18:10,000 --> 00:18:14,000
+Thus, they announce again, Single-A.
+
+241
+00:18:15,000 --> 00:18:21,000
+There might be different reasons to use single for table names, but in my opinion, these are the most
+
+242
+00:18:21,000 --> 00:18:21,000
+important ones.
+
+243
+00:18:22,000 --> 00:18:23,000
+I wouldn't like to use that.
+
+244
+00:18:23,000 --> 00:18:30,000
+I always worked on the projects where tables were named as singular, sometimes so rotten project where
+
+245
+00:18:30,000 --> 00:18:36,000
+we use plural for database tables, names and remember the main sink in.
+
+246
+00:18:36,000 --> 00:18:38,000
+Each naming convention is consistency.
+
+247
+00:18:39,000 --> 00:18:44,000
+The whole team agreed to follow some specific naming convention and different generation of programmers.
+
+248
+00:18:44,000 --> 00:18:50,000
+Since this project also understands this and agreed with this, then you don't have any problem at all.
+
+249
+00:18:50,000 --> 00:18:56,000
+And then comes a day your team might find logical the name container or froze with plural if container
+
+250
+00:18:56,000 --> 00:18:58,000
+contains users.
+
+251
+00:18:58,000 --> 00:19:05,000
+It is obvious that we have to name it users, but we also reviewed point of use that explains why this
+
+252
+00:19:05,000 --> 00:19:08,000
+might not always be the best way to name a table.
+
+253
+00:19:09,000 --> 00:19:14,000
+To be honest, it is hard for me to come up with other advantages of using plural names for tables.
+
+254
+00:19:15,000 --> 00:19:19,000
+Remember, it is always up to you what naming convention you are going to follow.
+
+255
+00:19:20,000 --> 00:19:26,000
+But the most important here is consistency in naming across different parts of your app.
+
+256
+00:19:26,000 --> 00:19:32,000
+I believe I answer to all concerns regarding the naming convention and why I named the bill in singular
+
+257
+00:19:32,000 --> 00:19:33,000
+form.
+
+258
+00:19:33,000 --> 00:19:34,000
+Let's proceed.
+
+259
+00:19:34,000 --> 00:19:40,000
+So you already know that you can set charset and collation on table level two.
+
+260
+00:19:40,000 --> 00:19:44,000
+Another interesting configuration here is an engine.
+
+261
+00:19:44,000 --> 00:19:45,000
+Let's talk about it now.
+
+262
+00:19:46,000 --> 00:19:50,000
+Let me explain you more about search engines in my school.
+
+263
+00:19:50,000 --> 00:19:57,000
+The search engine is a software module that database management system uses for me operations with data
+
+264
+00:19:58,000 --> 00:20:00,000
+such as Create, Read, Update, Delete.
+
+265
+00:20:01,000 --> 00:20:08,000
+Generally speaking, there are two types of storage engines in my school transactional and non transactional.
+
+266
+00:20:08,000 --> 00:20:11,000
+In my school, we have nine types of storage engines.
+
+267
+00:20:12,000 --> 00:20:15,000
+Two campuses was a school bus.
+
+268
+00:20:15,000 --> 00:20:17,000
+With schools, there's one storage engine.
+
+269
+00:20:18,000 --> 00:20:24,000
+It is very important to select the right search engine because this is strategic decision that will
+
+270
+00:20:24,000 --> 00:20:25,000
+impact future development.
+
+271
+00:20:25,000 --> 00:20:32,000
+The default search engine in my school is in the B from version five point five and later.
+
+272
+00:20:32,000 --> 00:20:34,000
+Previously, it was my is some.
+
+273
+00:20:35,000 --> 00:20:38,000
+Let me very briefly cover each storage engine in order.
+
+274
+00:20:38,000 --> 00:20:40,000
+You could understand the difference.
+
+275
+00:20:41,000 --> 00:20:46,000
+In a debate is the most widely used storage engine with transaction support.
+
+276
+00:20:46,000 --> 00:20:53,000
+It is an acid compliant storage engine as it compliant means it meets requirements for transactions
+
+277
+00:20:54,000 --> 00:20:59,000
+as it is an acronym that stands for atomic consistent, independent, durable.
+
+278
+00:21:00,000 --> 00:21:04,000
+These are properties of transactions that we are going to cover in detail.
+
+279
+00:21:04,000 --> 00:21:11,000
+A lesson about transactions in a the B supports roll level locking crash recovery and motivation version
+
+280
+00:21:11,000 --> 00:21:13,000
+concurrency control.
+
+281
+00:21:13,000 --> 00:21:18,000
+It is the only engine which provides foreign key, referential integrity constrained.
+
+282
+00:21:19,000 --> 00:21:26,000
+Oracle recommends using Unity B for tables except for specialized use cases, and thus the search engine
+
+283
+00:21:26,000 --> 00:21:27,000
+is my is.
+
+284
+00:21:27,000 --> 00:21:31,000
+The main difference from Inada be it is not transactional one.
+
+285
+00:21:32,000 --> 00:21:34,000
+It is a relatively fast storage engine.
+
+286
+00:21:35,000 --> 00:21:39,000
+But as we already said, it doesn't support transactions.
+
+287
+00:21:39,000 --> 00:21:42,000
+My ISA provides stable level locking.
+
+288
+00:21:42,000 --> 00:21:45,000
+It is used mostly in lab and data warehousing.
+
+289
+00:21:46,000 --> 00:21:49,000
+Let me say now a few words about memory storage engine.
+
+290
+00:21:50,000 --> 00:21:56,000
+It is named, so because it creates tables in memory, it is the fastest engine.
+
+291
+00:21:56,000 --> 00:21:58,000
+It provides stable level locking.
+
+292
+00:21:59,000 --> 00:22:01,000
+It doesn't support transactions.
+
+293
+00:22:01,000 --> 00:22:06,000
+Memory storage engine is ideal for creating temporary tables or quick look ups.
+
+294
+00:22:07,000 --> 00:22:10,000
+The data is lost when the database is restarted.
+
+295
+00:22:10,000 --> 00:22:16,000
+Different news There are not so many use cases for the search engine because each application requires
+
+296
+00:22:16,000 --> 00:22:17,000
+persistent storage.
+
+297
+00:22:18,000 --> 00:22:21,000
+See, a Swiss storage engine has specific formats of the stored data.
+
+298
+00:22:22,000 --> 00:22:24,000
+It stores data in CSP files.
+
+299
+00:22:24,000 --> 00:22:31,000
+It provides great flexibility because data in this format is easily integrated into other applications.
+
+300
+00:22:31,000 --> 00:22:35,000
+Match operates on underlying might e some tables.
+
+301
+00:22:35,000 --> 00:22:39,000
+Match tables help manage large volume of data more easily.
+
+302
+00:22:40,000 --> 00:22:46,000
+It logically groups a series of identical might use some tables and references them as one object.
+
+303
+00:22:46,000 --> 00:22:53,000
+Good for data warehousing environments Archive search engine is optimized for high speed and certain
+
+304
+00:22:54,000 --> 00:22:56,000
+it compresses data as it is inserted.
+
+305
+00:22:57,000 --> 00:22:59,000
+It doesn't support transactions.
+
+306
+00:22:59,000 --> 00:23:07,000
+It is a yield for storing and retrieving large amounts of seldom referenced historical archive data.
+
+307
+00:23:08,000 --> 00:23:14,000
+The black hole search engine accepts but doesn't store data which reveals always written and them to
+
+308
+00:23:14,000 --> 00:23:16,000
+set critical feature.
+
+309
+00:23:16,000 --> 00:23:17,000
+Don't you think so?
+
+310
+00:23:17,000 --> 00:23:18,000
+And I understand your feeling.
+
+311
+00:23:19,000 --> 00:23:25,000
+Probably it is not so easy to come up with the use case for such storing engine, but I have few use
+
+312
+00:23:25,000 --> 00:23:28,000
+cases when this might come in handy.
+
+313
+00:23:28,000 --> 00:23:34,000
+The French analogy can be used in distributed database design, where data is automatically replicated
+
+314
+00:23:34,000 --> 00:23:37,000
+but not stored locally and also does.
+
+315
+00:23:37,000 --> 00:23:42,000
+This search engine can be used to execute performance tests or other testing.
+
+316
+00:23:43,000 --> 00:23:49,000
+Federated Search Engine offers the ability to separate my Secret Service to create one logical database
+
+317
+00:23:49,000 --> 00:23:51,000
+from many physical service.
+
+318
+00:23:51,000 --> 00:23:57,000
+Queries on the local server are automatically executed on the remote federated tables.
+
+319
+00:23:57,000 --> 00:24:00,000
+No data is stored on the local tables.
+
+320
+00:24:00,000 --> 00:24:07,000
+It is good for distributed environments, and the B cluster is an in-memory storage engine, offering
+
+321
+00:24:07,000 --> 00:24:10,000
+high availability and data persistence features.
+
+322
+00:24:11,000 --> 00:24:18,000
+The engine cluster storage engine can be configured with a range or fail over and load balancing options.
+
+323
+00:24:18,000 --> 00:24:25,000
+Using SQL notes is the most common way of executing queries, and SQL note is the same as an instance
+
+324
+00:24:25,000 --> 00:24:33,000
+of my SQL server was the NDB storage engine compiled in the NDB search engine provides a breach from
+
+325
+00:24:33,000 --> 00:24:34,000
+my SQL server.
+
+326
+00:24:34,000 --> 00:24:41,000
+List of data nodes and DB search engine is implemented using a distributed shared nutzen architecture,
+
+327
+00:24:42,000 --> 00:24:47,000
+which causes it to behave differently from anybody b in a number of ways.
+
+328
+00:24:47,000 --> 00:24:55,000
+For those unaccustomed to work and was NDB, unexpected behaviors can arise is distributed nature with
+
+329
+00:24:55,000 --> 00:25:01,000
+regard to transactions for in case table limits and other characteristics.
+
+330
+00:25:01,000 --> 00:25:07,000
+This is not so easy to explain in a few sentences, but in general, if you are interested, you can
+
+331
+00:25:07,000 --> 00:25:12,000
+ask is a specific question about the search engine or find documentation on my SQL side.
+
+332
+00:25:13,000 --> 00:25:17,000
+So what search engine to choose among such variety?
+
+333
+00:25:17,000 --> 00:25:23,000
+It depends on the up to you and business problem you are trying to address and once saying you should
+
+334
+00:25:23,000 --> 00:25:29,000
+remember for sure, there is no perfect search engine littered with works the best in all possible cases.
+
+335
+00:25:29,000 --> 00:25:35,000
+Some of them better under certain conditions and perform worse in other situations, and some of them
+
+336
+00:25:35,000 --> 00:25:36,000
+vice versa.
+
+337
+00:25:37,000 --> 00:25:41,000
+In software engineering, it is always a matter of tradeoffs and.
+
+338
+00:25:41,000 --> 00:25:43,000
+Most secure solution takes more resources.
+
+339
+00:25:44,000 --> 00:25:48,000
+Thus, it might be slower, take more CPU time and disk space.
+
+340
+00:25:49,000 --> 00:25:54,000
+But you should understand that you have not one but nine storage engines.
+
+341
+00:25:54,000 --> 00:26:00,000
+And my sequel is very flexible in the fact that it provides several different storage engines.
+
+342
+00:26:00,000 --> 00:26:05,000
+Some of them, like archive engine, are created to be used in specific situations.
+
+343
+00:26:06,000 --> 00:26:13,000
+In some cases, the answer is clear whenever we're dealing with some payment systems, we are obligated
+
+344
+00:26:13,000 --> 00:26:15,000
+to use the transactional storage.
+
+345
+00:26:15,000 --> 00:26:21,000
+We cannot afford to lose such sensitive data in a debate is the way to go.
+
+346
+00:26:22,000 --> 00:26:27,000
+If we want full text search, then we can choose is a mighty sum or in the be.
+
+347
+00:26:28,000 --> 00:26:33,000
+Now, you know, the difference between different storage engines in our particular case.
+
+348
+00:26:33,000 --> 00:26:38,000
+Let's keep the default one here, so I keep an eye on the Beast search engine.
+
+349
+00:26:38,000 --> 00:26:41,000
+After that, we can proceed with declaring columns.
+
+350
+00:26:41,000 --> 00:26:42,000
+Let's use surrogate.
+
+351
+00:26:42,000 --> 00:26:48,000
+Primary key was name I.D. for each row, and let's make it of type in.
+
+352
+00:26:49,000 --> 00:26:53,000
+You have to fill out column name, data type and set column properties.
+
+353
+00:26:54,000 --> 00:26:59,000
+We are going to learn more about each column property right after we finish a discussion about data
+
+354
+00:26:59,000 --> 00:26:59,000
+types.
+
+355
+00:27:00,000 --> 00:27:06,000
+As you see, each column will have its own data type, then different types and different relational
+
+356
+00:27:06,000 --> 00:27:11,000
+database management systems, but more or less this similar in my cycle.
+
+357
+00:27:11,000 --> 00:27:19,000
+All data types might be grouped into the next categories numeric data types date and time data types
+
+358
+00:27:20,000 --> 00:27:29,000
+string data types spatial data types My circle supports geometry types of point lines, string, polygon
+
+359
+00:27:29,000 --> 00:27:37,000
+multipoint, multi-line string, multi polygon and Geometry Collection OSR geometry types are not supported.
+
+360
+00:27:38,000 --> 00:27:44,000
+JSON data type most likely will not go over each and every possible data type.
+
+361
+00:27:44,000 --> 00:27:52,000
+In my school, I prepared slides to cover the most popular numeric date and time and string data types.
+
+362
+00:27:53,000 --> 00:27:59,000
+On this slide, you can find numeric data types, I suppose, for a minute if you want to read comments
+
+363
+00:27:59,000 --> 00:28:05,000
+for each particular data type here, but in most cases you are going to use and type.
+
+364
+00:28:06,000 --> 00:28:09,000
+That is my opinion, probably sometimes.
+
+365
+00:28:09,000 --> 00:28:11,000
+So I'm going to use other data types too.
+
+366
+00:28:11,000 --> 00:28:19,000
+But in time is generally enough, especially if we use unsigned and you have one more additional beat
+
+367
+00:28:19,000 --> 00:28:26,000
+to store information and attention in this list, you have both integers and floating point numbers,
+
+368
+00:28:26,000 --> 00:28:32,000
+so you can select data type for your columns that meets business needs to store value.
+
+369
+00:28:32,000 --> 00:28:40,000
+On this slide, you can find data types that will help you to represent date and time in database humorists
+
+370
+00:28:40,000 --> 00:28:47,000
+or date or time separately, or you can store data time looking with date and time.
+
+371
+00:28:47,000 --> 00:28:49,000
+And what original app always was a patent?
+
+372
+00:28:50,000 --> 00:28:50,000
+Why?
+
+373
+00:28:51,000 --> 00:28:58,000
+First of all, for Martin, during the storm and database and retrieved from database, it seems to
+
+374
+00:28:58,000 --> 00:28:59,000
+be like a simple scene.
+
+375
+00:28:59,000 --> 00:29:06,000
+But I promise you, at least someone from your team will mess up was for the second things that might
+
+376
+00:29:06,000 --> 00:29:08,000
+be challenging time zones.
+
+377
+00:29:09,000 --> 00:29:12,000
+Team, believe me, time zones are very, very painful.
+
+378
+00:29:13,000 --> 00:29:20,000
+Some engineers use time stamp to store a number of seconds since Unix epoch, but there is a specific
+
+379
+00:29:20,000 --> 00:29:23,000
+range of data that is supported by my SQL by default.
+
+380
+00:29:23,000 --> 00:29:30,000
+So one of us options, probably it is not super duper popular, but still look around.
+
+381
+00:29:30,000 --> 00:29:31,000
+It deserves to leave.
+
+382
+00:29:32,000 --> 00:29:40,000
+You can use even in data types to serve milliseconds from Unix epoch heaven, time and milliseconds.
+
+383
+00:29:40,000 --> 00:29:46,000
+You can convert it in any app any day during the conversion in both direction.
+
+384
+00:29:46,000 --> 00:29:48,000
+You can consider time zone of the user.
+
+385
+00:29:49,000 --> 00:29:53,000
+In this case, all milliseconds would be according to UTC.
+
+386
+00:29:53,000 --> 00:29:56,000
+The Understand what I'm talking about.
+
+387
+00:29:56,000 --> 00:29:58,000
+Remember this workaround?
+
+388
+00:29:58,000 --> 00:30:03,000
+It might help you some day and no matter what application you will work with.
+
+389
+00:30:03,000 --> 00:30:09,000
+And also, if you want to learn more about date and time in Java, please refer to my Java course.
+
+390
+00:30:09,000 --> 00:30:15,000
+I have separate lessons, dedicated time zones and working with date and time in Java programs.
+
+391
+00:30:15,000 --> 00:30:21,000
+And on this slide, you can see a list of data types that you can use to store text values.
+
+392
+00:30:21,000 --> 00:30:27,000
+One of the differences between all these types is amount of memory that is reserved to stores.
+
+393
+00:30:27,000 --> 00:30:33,000
+The value in this field bressan course if you want to check comments for each day that that.
+
+394
+00:30:34,000 --> 00:30:37,000
+So we learned what data types might be used for columns.
+
+395
+00:30:38,000 --> 00:30:40,000
+Now let's learn another thing.
+
+396
+00:30:40,000 --> 00:30:42,000
+Let's talk about column properties.
+
+397
+00:30:43,000 --> 00:30:45,000
+You can see different letters here.
+
+398
+00:30:45,000 --> 00:30:49,000
+And also the checkbox here they are the same.
+
+399
+00:30:50,000 --> 00:30:52,000
+Let's learn what those they meant.
+
+400
+00:30:53,000 --> 00:30:59,000
+K stands for primary key and N stands for Not Now You.
+
+401
+00:30:59,000 --> 00:31:01,000
+Q stands for unique.
+
+402
+00:31:01,000 --> 00:31:03,000
+This creates unique index.
+
+403
+00:31:03,000 --> 00:31:06,000
+We're going to learn about indexes in the separate lesson.
+
+404
+00:31:07,000 --> 00:31:10,000
+B stands for binary stores data as binary strings.
+
+405
+00:31:11,000 --> 00:31:18,000
+There is no character set so certain, and comparison is based on the numerical values of the bytes
+
+406
+00:31:18,000 --> 00:31:21,000
+in the values you and stands for.
+
+407
+00:31:21,000 --> 00:31:21,000
+And.
+
+408
+00:31:22,000 --> 00:31:27,000
+That is property for all no data types that allows you to store only positive numbers.
+
+409
+00:31:28,000 --> 00:31:30,000
+ZF stands for zero field.
+
+410
+00:31:30,000 --> 00:31:32,000
+This is an interesting one.
+
+411
+00:31:32,000 --> 00:31:39,000
+I need to demo this will use zero field property for one of the fields just in demo purposes.
+
+412
+00:31:39,000 --> 00:31:44,000
+In short, it feels with zero all the lengths reserved for value.
+
+413
+00:31:44,000 --> 00:31:47,000
+Eight AI stands for auto increment.
+
+414
+00:31:47,000 --> 00:31:50,000
+No value can be increased by one.
+
+415
+00:31:50,000 --> 00:31:55,000
+Usually, this one is used for surrogate primary keys in order that the base can generate unique number
+
+416
+00:31:55,000 --> 00:32:05,000
+for ID field by increment in values with each new record inserted and G stands for generated, the value
+
+417
+00:32:05,000 --> 00:32:09,000
+is generated by a formula based on other columns.
+
+418
+00:32:10,000 --> 00:32:17,000
+If the field is primary key, that means that this field will have only unique values, not new values.
+
+419
+00:32:17,000 --> 00:32:21,000
+Additionally, I recommend you to at all to increment property.
+
+420
+00:32:21,000 --> 00:32:27,000
+This will automatically increment your I.D. integer value on each new insertion.
+
+421
+00:32:28,000 --> 00:32:30,000
+In this case, you shouldn't be to.
+
+422
+00:32:30,000 --> 00:32:32,000
+It's a generation of unique I.D..
+
+423
+00:32:33,000 --> 00:32:39,000
+Also, I want to use unsigned integer values in order to increase range of positive numbers that can
+
+424
+00:32:39,000 --> 00:32:40,000
+be used as I.D..
+
+425
+00:32:41,000 --> 00:32:44,000
+Let's also create a few more fields of virtual time.
+
+426
+00:32:45,000 --> 00:32:50,000
+We're going to create first name, last name and email to create each new field.
+
+427
+00:32:50,000 --> 00:32:53,000
+Just press on empty space.
+
+428
+00:32:55,000 --> 00:33:02,000
+I will create unique index for email column to make performance of extract any user by email data and
+
+429
+00:33:02,000 --> 00:33:03,000
+cluster.
+
+430
+00:33:06,000 --> 00:33:12,000
+According to naming convention, we use lowercase and the words are separated, which underscores their
+
+431
+00:33:12,000 --> 00:33:17,000
+tension that you have to specify maximum length of zero hour char.
+
+432
+00:33:17,000 --> 00:33:25,000
+By default, this forty five characters you can just click in data era type and change this limit.
+
+433
+00:33:26,000 --> 00:33:31,000
+And as I said, let me demo zero field property for our property.
+
+434
+00:33:31,000 --> 00:33:34,000
+We would adjust lengths of data time to five.
+
+435
+00:33:35,000 --> 00:33:38,000
+Also, we will select the checkbox.
+
+436
+00:33:38,000 --> 00:33:45,000
+So when you're ready, you can click Apply button sequel query will be shown for you to approve.
+
+437
+00:33:46,000 --> 00:33:48,000
+We're going to learn SQL in a separate lessons.
+
+438
+00:33:48,000 --> 00:33:54,000
+We'll also cover create table statements, but you already can start at least watching at these queries.
+
+439
+00:33:55,000 --> 00:33:56,000
+Click Apply Button.
+
+440
+00:33:57,000 --> 00:34:03,000
+Now, when our query is applied, we can find our table on the tables in our databases.
+
+441
+00:34:04,000 --> 00:34:07,000
+Let's expand that, and here's how I use our table.
+
+442
+00:34:07,000 --> 00:34:09,000
+Congratulations.
+
+443
+00:34:09,000 --> 00:34:11,000
+We have created our first table.
+
+444
+00:34:12,000 --> 00:34:19,000
+The looks are zeroes, mouse, right click select rows, and you can see separate up was sequel query
+
+445
+00:34:19,000 --> 00:34:22,000
+executed and representation of your table.
+
+446
+00:34:22,000 --> 00:34:25,000
+You can play with the stable by entering different values.
+
+447
+00:34:26,000 --> 00:34:27,000
+There are tensions.
+
+448
+00:34:27,000 --> 00:34:34,000
+Its values in email column should be unique, and you don't need to populate the column because it is
+
+449
+00:34:34,000 --> 00:34:35,000
+all the it.
+
+450
+00:34:42,000 --> 00:34:49,000
+Once you adjust that table, click Apply button again, you will see preview of insert statements,
+
+451
+00:34:49,000 --> 00:34:51,000
+click Apply one more time.
+
+452
+00:34:52,000 --> 00:34:58,000
+And now you can see that I.D. values have been generated and pay attention to the format.
+
+453
+00:34:58,000 --> 00:35:05,000
+The lengths of these five digits enumeration is going according to the regular number sequence, and
+
+454
+00:35:05,000 --> 00:35:07,000
+the rest digits are filled with zero.
+
+455
+00:35:08,000 --> 00:35:10,000
+That's what zero field property does.
+
+456
+00:35:11,000 --> 00:35:15,000
+But to be honest, I don't use this option very often.
+
+457
+00:35:15,000 --> 00:35:17,000
+But at least now you know what it does.
+
+458
+00:35:18,000 --> 00:35:19,000
+Wow.
+
+459
+00:35:19,000 --> 00:35:21,000
+We have learned a lot for the.
+
+460
+00:35:21,000 --> 00:35:24,000
+Let's recap what we have learned in this lesson.
+
+461
+00:35:25,000 --> 00:35:28,000
+In this lesson, we created our schema.
+
+462
+00:35:28,000 --> 00:35:33,000
+We learned what charset and collation is and which one I recommend to use.
+
+463
+00:35:34,000 --> 00:35:39,000
+You're in the lesson recovery topic of naming conventions for database objects.
+
+464
+00:35:39,000 --> 00:35:43,000
+Now, you know, recommended rules to follow during the naming of schemas.
+
+465
+00:35:43,000 --> 00:35:44,000
+Tables and columns.
+
+466
+00:35:45,000 --> 00:35:48,000
+After this lesson, you know what search engines are.
+
+467
+00:35:48,000 --> 00:35:54,000
+And you know, the difference between nine search engines in my school would have used different data
+
+468
+00:35:54,000 --> 00:35:55,000
+types in my school.
+
+469
+00:35:56,000 --> 00:36:02,000
+And at the end of the lesson, we learned column properties and create a table in database.
+
+470
+00:36:02,000 --> 00:36:04,000
+Thanks a lot for your attention.
+
+471
+00:36:04,000 --> 00:36:05,000
+Have a great day.
+
+472
+00:36:05,000 --> 00:36:07,000
+See you in the next lesson.
+

47 - Relational databases/003 Referential Integrity Foreign Key Constraint & Cascading Operations_en.srt

@@ -0,0 +1,1064 @@
+1
+00:00:05,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:06,000 --> 00:00:12,000
+Today we're going to proceed our practical activities combined with some new piece of theory.
+
+3
+00:00:12,000 --> 00:00:18,000
+In this video, we proceed working with our first database tables that we created in the previous lesson.
+
+4
+00:00:19,000 --> 00:00:25,000
+We are going to learn more about referential integrity, foreign key constraints and cascading operations.
+
+5
+00:00:26,000 --> 00:00:32,000
+We'll start our lesson from understanding of referential integrity and potential consequences in case
+
+6
+00:00:32,000 --> 00:00:33,000
+it will be broken.
+
+7
+00:00:33,000 --> 00:00:39,000
+After that, we'll focus our attention on the solution for broken, referential integrity and how to
+
+8
+00:00:39,000 --> 00:00:41,000
+what is happening in your database.
+
+9
+00:00:42,000 --> 00:00:48,000
+We are going to review what cascading operations are and understand different types of cost-cutting
+
+10
+00:00:48,000 --> 00:00:49,000
+operations.
+
+11
+00:00:49,000 --> 00:00:56,000
+After that and practice, we are going to configure a foreign key constraint after review of all examples.
+
+12
+00:00:56,000 --> 00:01:02,000
+And by the end of this lesson, I am sure you will understand such concepts as data consistency, data
+
+13
+00:01:02,000 --> 00:01:05,000
+integrity, data quality and data validity.
+
+14
+00:01:06,000 --> 00:01:07,000
+Let's start the lesson.
+
+15
+00:01:08,000 --> 00:01:14,000
+And before we start altering our database table, let's try to understand problems that we are going
+
+16
+00:01:14,000 --> 00:01:15,000
+to avoid.
+
+17
+00:01:15,000 --> 00:01:18,000
+Let's talk about referential integrity.
+
+18
+00:01:19,000 --> 00:01:25,000
+Referential integrity is one of the most important and mandatory property in the relational database
+
+19
+00:01:25,000 --> 00:01:28,000
+that ensures that all references are valid.
+
+20
+00:01:29,000 --> 00:01:35,000
+So in case one attribute of a relational table reference is the value of another attribute, then the
+
+21
+00:01:35,000 --> 00:01:38,000
+reference value must exist.
+
+22
+00:01:39,000 --> 00:01:40,000
+In simple words.
+
+23
+00:01:40,000 --> 00:01:48,000
+Then it means that there are no references made by foreign keys to non-existent typos and to simplify
+
+24
+00:01:48,000 --> 00:01:49,000
+it even more.
+
+25
+00:01:49,000 --> 00:01:52,000
+It prohibits relations between tables using foreign keys.
+
+26
+00:01:53,000 --> 00:02:00,000
+We have to be sure that foreign key is referencing to valid and existing data because otherwise it is
+
+27
+00:02:00,000 --> 00:02:07,000
+not clear how to build relations between entities and case parent entity is not present in database
+
+28
+00:02:07,000 --> 00:02:08,000
+anymore.
+
+29
+00:02:09,000 --> 00:02:11,000
+Why referential integrity is important.
+
+30
+00:02:11,000 --> 00:02:16,000
+There are different issues that mafia during the corruption of referential integrity.
+
+31
+00:02:17,000 --> 00:02:23,000
+But the root cause of all issues is lost data because of corrupted integrity.
+
+32
+00:02:23,000 --> 00:02:31,000
+A lack of referential integrity in the database can lead to incomplete data being churned, sometimes
+
+33
+00:02:31,000 --> 00:02:33,000
+even with no indication of an error.
+
+34
+00:02:34,000 --> 00:02:41,000
+This could result in the records being lost in the database because there's never a chance inquiries
+
+35
+00:02:41,000 --> 00:02:44,000
+or reports, and the consequences might be different.
+
+36
+00:02:45,000 --> 00:02:50,000
+Your existing queries may not transcend specific fields from other tables.
+
+37
+00:02:50,000 --> 00:02:58,000
+Neurons across tune queries and this will produce some system error because the logic in court is usually
+
+38
+00:02:58,000 --> 00:03:04,000
+built in rounds of data to modify it and to process and use some data is absent.
+
+39
+00:03:05,000 --> 00:03:07,000
+Required logic is not triggered.
+
+40
+00:03:07,000 --> 00:03:16,000
+So I want you to understand that this is not just data consistency issue referential integrity potentially
+
+41
+00:03:16,000 --> 00:03:19,000
+may lead to not expected program behavior.
+
+42
+00:03:20,000 --> 00:03:25,000
+Let's review example of a problem, and let's try to find a solution for it.
+
+43
+00:03:25,000 --> 00:03:27,000
+Imagine that we have two tables.
+
+44
+00:03:28,000 --> 00:03:30,000
+They are user and roll.
+
+45
+00:03:31,000 --> 00:03:33,000
+Each user should have a role.
+
+46
+00:03:33,000 --> 00:03:38,000
+It can be user admin or content editor or employee or client.
+
+47
+00:03:39,000 --> 00:03:44,000
+There might be different roles here, but what is important?
+
+48
+00:03:44,000 --> 00:03:49,000
+There is one too many relationships between the role table and user table.
+
+49
+00:03:49,000 --> 00:03:55,000
+Each user may have only one role and each role may be assigned to multiple users.
+
+50
+00:03:56,000 --> 00:04:03,000
+And now imagine that we decided to remove content editor role and we decided to introduce different
+
+51
+00:04:03,000 --> 00:04:07,000
+roles in Step Media Editor and contributor.
+
+52
+00:04:08,000 --> 00:04:14,000
+Well, not that depends a business domain, because anyway, I want you to focus not on the specific
+
+53
+00:04:14,000 --> 00:04:22,000
+business issue, but on the technical one and step one of the role of TOPO is it contained information
+
+54
+00:04:22,000 --> 00:04:23,000
+about content editor.
+
+55
+00:04:23,000 --> 00:04:27,000
+What shall we do with foreign keys in our user table?
+
+56
+00:04:27,000 --> 00:04:31,000
+They still reference to the table that doesn't exist anymore.
+
+57
+00:04:32,000 --> 00:04:33,000
+Do understands the problem.
+
+58
+00:04:34,000 --> 00:04:41,000
+In case I would need to get full name for all users, what will I get for users that have known about
+
+59
+00:04:41,000 --> 00:04:42,000
+its reference?
+
+60
+00:04:42,000 --> 00:04:47,000
+This is exactly the problem that is caused by corruption of referential integrity.
+
+61
+00:04:48,000 --> 00:04:53,000
+How to prevent this happen, we need to set up foreign key constraint.
+
+62
+00:04:54,000 --> 00:04:56,000
+Let's understand now what it is.
+
+63
+00:04:57,000 --> 00:05:03,000
+The foreign key constraint is used to prevent actions that will destroy links between tables.
+
+64
+00:05:04,000 --> 00:05:11,000
+A foreign key is a field or collection of fields in one table that refers to the primary key in another
+
+65
+00:05:11,000 --> 00:05:12,000
+table.
+
+66
+00:05:12,000 --> 00:05:18,000
+The table with foreign key is called the child table, and the table was the primary.
+
+67
+00:05:18,000 --> 00:05:22,000
+Key is called the reference or parent table.
+
+68
+00:05:22,000 --> 00:05:29,000
+In our particular example, user table contains column was named after a user role.
+
+69
+00:05:29,000 --> 00:05:36,000
+This is exactly foreign key that allows us to build relationships between user and role tables.
+
+70
+00:05:37,000 --> 00:05:43,000
+Now, let's think how we can figure that issue was foreign key constraint and how exactly it will prevent
+
+71
+00:05:43,000 --> 00:05:45,000
+corruption of referential integrity.
+
+72
+00:05:46,000 --> 00:05:51,000
+Let me suggest a few ideas how to avoid corruption of referential integrity.
+
+73
+00:05:51,000 --> 00:05:59,000
+The first option is just to forbid removal and the date of Toptal in case some other tables contains
+
+74
+00:05:59,000 --> 00:06:00,000
+a reference to it.
+
+75
+00:06:00,000 --> 00:06:08,000
+In this case, we can't remove content editor role or update its I-D until some references exist.
+
+76
+00:06:09,000 --> 00:06:12,000
+The second option is to remove all related records.
+
+77
+00:06:12,000 --> 00:06:19,000
+For example, if I remove content editor role, then keeping content editor users in the system makes
+
+78
+00:06:19,000 --> 00:06:22,000
+no sense, and I also remove related users.
+
+79
+00:06:23,000 --> 00:06:31,000
+Now, imagine that instead of removing Content Editor, you just decided to update it and you change
+
+80
+00:06:31,000 --> 00:06:33,000
+the primary key and the role name.
+
+81
+00:06:33,000 --> 00:06:37,000
+In this case, we update all references was updated primary key.
+
+82
+00:06:38,000 --> 00:06:42,000
+Another option is to set null values instead of all references.
+
+83
+00:06:43,000 --> 00:06:50,000
+You may also consider this option, but again, in this case, you have to have logical place that process
+
+84
+00:06:50,000 --> 00:06:54,000
+null values that you would receive in response instead of required data.
+
+85
+00:06:55,000 --> 00:07:02,000
+And all value is a special marker used in school to indicate that a data value doesn't exist in the
+
+86
+00:07:02,000 --> 00:07:03,000
+database.
+
+87
+00:07:04,000 --> 00:07:11,000
+In other words, it is just a placeholder to denote values that missing was that we don't know.
+
+88
+00:07:12,000 --> 00:07:19,000
+And last but not least, is setting default value instead of all references, for example, in this
+
+89
+00:07:19,000 --> 00:07:22,000
+case, one content editor role has been removed.
+
+90
+00:07:23,000 --> 00:07:26,000
+We can set default reference to employee role records.
+
+91
+00:07:27,000 --> 00:07:34,000
+That means that all references to Content Editor role will be substituted with references to employee
+
+92
+00:07:34,000 --> 00:07:34,000
+role.
+
+93
+00:07:36,000 --> 00:07:39,000
+All these options are called cascading operations.
+
+94
+00:07:40,000 --> 00:07:47,000
+These operations are special kind of database restrictions that describe his behavior in case of removal
+
+95
+00:07:47,000 --> 00:07:53,000
+record from parent table or in case updating of its primary key.
+
+96
+00:07:53,000 --> 00:07:54,000
+Does it make sense?
+
+97
+00:07:55,000 --> 00:08:02,000
+And then the lesson we are going to learn how to set up these restrictions in our table on practice.
+
+98
+00:08:03,000 --> 00:08:10,000
+So to sum it up, we can configure foreign key constraint on update or on the lead off primary key in
+
+99
+00:08:10,000 --> 00:08:11,000
+parent table.
+
+100
+00:08:12,000 --> 00:08:17,000
+Foreign key constraint may be of the following types restrict.
+
+101
+00:08:17,000 --> 00:08:25,000
+This restricts any cost current operations, so we have to make sure first that we removed all references
+
+102
+00:08:25,000 --> 00:08:33,000
+to this table and only after that remove or update the primary key in parent table cascade.
+
+103
+00:08:34,000 --> 00:08:41,000
+This option will update foreign key in child tables in case it was updated and will remove double from
+
+104
+00:08:41,000 --> 00:08:46,000
+child table in case primary key and parent table has been removed.
+
+105
+00:08:46,000 --> 00:08:53,000
+Set now based on the name, you can make an assumption what does assumption that it sets?
+
+106
+00:08:53,000 --> 00:08:58,000
+Now, instead of foreign key, it's the last one was either updated or removed.
+
+107
+00:08:59,000 --> 00:09:00,000
+No action.
+
+108
+00:09:01,000 --> 00:09:03,000
+Is this a so-so options of disposable tissues?
+
+109
+00:09:03,000 --> 00:09:10,000
+But I'm not sure whether you will need it, because the whole idea of foreign key constraint is to set
+
+110
+00:09:10,000 --> 00:09:16,000
+up a constraint, but not just select no action option and ignore things, said default.
+
+111
+00:09:17,000 --> 00:09:21,000
+You can substitute reference to the foreign key was the default value.
+
+112
+00:09:22,000 --> 00:09:28,000
+While this is also one of the foreign key constraints, you won't be able to find this option in my
+
+113
+00:09:28,000 --> 00:09:29,000
+school workbench.
+
+114
+00:09:30,000 --> 00:09:37,000
+Also, you wouldn't be able to set said default option or be a sequel query because it is simply not
+
+115
+00:09:37,000 --> 00:09:41,000
+supported by inadequate storage engine in my school.
+
+116
+00:09:41,000 --> 00:09:47,000
+Still, there is a workaround was usage of triggers in my school, but we haven't learned how to work
+
+117
+00:09:47,000 --> 00:09:49,000
+with triggers in a separate lesson.
+
+118
+00:09:50,000 --> 00:09:53,000
+And now there's exactly time for the live demo.
+
+119
+00:09:53,000 --> 00:09:56,000
+Let's learn in practice how to set foreign key constraint.
+
+120
+00:09:58,000 --> 00:10:05,000
+Bruce Larson, we created with you user table in case you didn't watch that lesson and don't know how
+
+121
+00:10:05,000 --> 00:10:06,000
+to create tables.
+
+122
+00:10:06,000 --> 00:10:09,000
+Please watch it if you have a user table.
+
+123
+00:10:10,000 --> 00:10:13,000
+We are going to proceed for the sake of the demo.
+
+124
+00:10:13,000 --> 00:10:15,000
+We need one more table.
+
+125
+00:10:15,000 --> 00:10:17,000
+Let's create role table now.
+
+126
+00:10:18,000 --> 00:10:23,000
+I already created this table before the lesson to save the time during the video lesson.
+
+127
+00:10:24,000 --> 00:10:30,000
+If you need time to create a table grasp, pause for a minute and then resume VIDEO when you are ready.
+
+128
+00:10:31,000 --> 00:10:33,000
+This table has only two fields.
+
+129
+00:10:33,000 --> 00:10:36,000
+They are ID and role name.
+
+130
+00:10:36,000 --> 00:10:37,000
+That's it.
+
+131
+00:10:38,000 --> 00:10:42,000
+When you created this table, please calculated, was valleys.
+
+132
+00:10:42,000 --> 00:10:45,000
+It is not critically important what would be a role name?
+
+133
+00:10:46,000 --> 00:10:50,000
+The main thing here is to have at least a few roles for demo purposes.
+
+134
+00:10:51,000 --> 00:10:57,000
+If you wish, you can create the values as I have, and when you add its values into the role table,
+
+135
+00:10:58,000 --> 00:10:59,000
+we are done with it.
+
+136
+00:10:59,000 --> 00:11:05,000
+And again, if you don't know how to add value in table, we are my school workbench.
+
+137
+00:11:06,000 --> 00:11:08,000
+Please refer to the previous lesson.
+
+138
+00:11:09,000 --> 00:11:13,000
+Now we need to establish relationships between the role and user tables.
+
+139
+00:11:14,000 --> 00:11:20,000
+If you remember lesson about relational database basic concepts, then you should remember that one
+
+140
+00:11:20,000 --> 00:11:25,000
+too many relationships is implemented by adding foreign key into another table.
+
+141
+00:11:26,000 --> 00:11:28,000
+We need to adjust our user table now.
+
+142
+00:11:29,000 --> 00:11:35,000
+I do mouse right click on the user table and I select Alter Table Option.
+
+143
+00:11:35,000 --> 00:11:40,000
+In this view, we need to add one more column for foreign key.
+
+144
+00:11:40,000 --> 00:11:47,000
+There is an agreed naming convention for the name of the foreign key, while you still can name it as
+
+145
+00:11:47,000 --> 00:11:48,000
+you want.
+
+146
+00:11:48,000 --> 00:11:57,000
+I would recommend you two fellows and next partner f k that stands for foreign key, followed by Underscore,
+
+147
+00:11:58,000 --> 00:12:00,000
+followed by foreign key table name.
+
+148
+00:12:00,000 --> 00:12:06,000
+In our case for table name is a target table xCurrent one.
+
+149
+00:12:06,000 --> 00:12:14,000
+Thus, I like to use R after f k after that again goes underscore, and this time it is followed by
+
+150
+00:12:14,000 --> 00:12:16,000
+primary key table.
+
+151
+00:12:16,000 --> 00:12:20,000
+This is our source table in this particular case.
+
+152
+00:12:20,000 --> 00:12:22,000
+This is roll table.
+
+153
+00:12:23,000 --> 00:12:28,000
+This is why we have such name for a foreign key column f k user role.
+
+154
+00:12:29,000 --> 00:12:36,000
+Considering that we use surrogate primary key in the role table, we have to use each type for the foreign
+
+155
+00:12:36,000 --> 00:12:37,000
+key column to.
+
+156
+00:12:39,000 --> 00:12:44,000
+When we are done with creation of the calling for the foreign key, let's open another tap.
+
+157
+00:12:44,000 --> 00:12:46,000
+I open foreign key staff.
+
+158
+00:12:47,000 --> 00:12:52,000
+This is exactly the type where we can configure foreign key constraint on the database level.
+
+159
+00:12:53,000 --> 00:12:55,000
+Specify foreign key name.
+
+160
+00:12:55,000 --> 00:13:00,000
+This is just a name for foreign key constraint in reference tables.
+
+161
+00:13:00,000 --> 00:13:03,000
+Select the parent table the tables.
+
+162
+00:13:03,000 --> 00:13:10,000
+It contains primary keys that we are referencing to, and after that you have opportunity to select.
+
+163
+00:13:10,000 --> 00:13:16,000
+The column was foreign key in the current table and specify reference column in the parent table.
+
+164
+00:13:17,000 --> 00:13:20,000
+Now why do we consider that connection?
+
+165
+00:13:20,000 --> 00:13:23,000
+Let me specify foreign key options here.
+
+166
+00:13:23,000 --> 00:13:30,000
+Usually, you can specify constraints on update and on delete operations in parenting mode for the sake
+
+167
+00:13:30,000 --> 00:13:31,000
+of the demo.
+
+168
+00:13:31,000 --> 00:13:34,000
+Let me set restrict options here.
+
+169
+00:13:34,000 --> 00:13:36,000
+I click apply by them.
+
+170
+00:13:36,000 --> 00:13:40,000
+You also can check SQL queries it is going to be executed.
+
+171
+00:13:41,000 --> 00:13:44,000
+Don't worry, one will come to learn in the sequel.
+
+172
+00:13:44,000 --> 00:13:47,000
+We are going to also cover alter table queries.
+
+173
+00:13:47,000 --> 00:13:51,000
+But still, it is good for you to be at least familiar with squares.
+
+174
+00:13:52,000 --> 00:13:59,000
+My concept of the Asian database is to let you understand operations that we need to execute against
+
+175
+00:13:59,000 --> 00:14:02,000
+database and when we need to execute them.
+
+176
+00:14:02,000 --> 00:14:11,000
+This gives my students understanding of end to end flow, and one will understand this will go to details
+
+177
+00:14:11,000 --> 00:14:13,000
+and will learn SQL itself.
+
+178
+00:14:13,000 --> 00:14:18,000
+I hope this approach will also help you to learn the topic faster.
+
+179
+00:14:19,000 --> 00:14:27,000
+In our user, a table, we have new fields now, let's put foreign keys for each user just to help you
+
+180
+00:14:27,000 --> 00:14:34,000
+understand I I.D. of Topo from rolls table to establish one to many relationships.
+
+181
+00:14:35,000 --> 00:14:39,000
+It isn't critically important in which one role will be assigned to each user.
+
+182
+00:14:40,000 --> 00:14:45,000
+Since this is all fake data, that's why I put these in random order.
+
+183
+00:14:45,000 --> 00:14:50,000
+Here is the interest in seeing the demo in roundtable.
+
+184
+00:14:50,000 --> 00:14:56,000
+We have maximum and equal to six basically Z values from one to six.
+
+185
+00:14:57,000 --> 00:15:05,000
+What will happen if I would try to set, for example, value 10 in foreign key column, I put Dan and
+
+186
+00:15:06,000 --> 00:15:07,000
+click Apply.
+
+187
+00:15:08,000 --> 00:15:13,000
+You can see that the reason there because was set, that'd be something like this.
+
+188
+00:15:13,000 --> 00:15:18,000
+This database, I want to establish relationships between two tables.
+
+189
+00:15:18,000 --> 00:15:23,000
+And this column will be used as foreign key to reference the parent table primary key.
+
+190
+00:15:24,000 --> 00:15:29,000
+And our database listen to us and do what we asked it to do.
+
+191
+00:15:29,000 --> 00:15:36,000
+That's why you can't add reference to non-existent primary key and parent table.
+
+192
+00:15:37,000 --> 00:15:38,000
+Let me open the roll table.
+
+193
+00:15:39,000 --> 00:15:45,000
+In case I'd like to remove all the participating relationships was record from another table.
+
+194
+00:15:45,000 --> 00:15:47,000
+I wouldn't be able to do that.
+
+195
+00:15:48,000 --> 00:15:51,000
+I can't do miles right click on the road and select the lead role.
+
+196
+00:15:52,000 --> 00:16:00,000
+After that, I click Apply button that the base doesn't let me remove zero because we restrict its removal
+
+197
+00:16:00,000 --> 00:16:04,000
+in this case, if you want to remove Roe was a new one.
+
+198
+00:16:04,000 --> 00:16:11,000
+We have to remove all references to this record in other tables, and only after that we will be able
+
+199
+00:16:11,000 --> 00:16:14,000
+to remove this rule does it make sense.
+
+200
+00:16:15,000 --> 00:16:19,000
+So our SQL query wasn't executed successfully.
+
+201
+00:16:19,000 --> 00:16:22,000
+That's why I click on Execute Query.
+
+202
+00:16:22,000 --> 00:16:27,000
+I can hear one more time, and here's our row back again.
+
+203
+00:16:28,000 --> 00:16:35,000
+It is still stored in Libby and is always guys not shy to ask questions and comments on this, we knew
+
+204
+00:16:35,000 --> 00:16:36,000
+in case you have any.
+
+205
+00:16:37,000 --> 00:16:39,000
+I always will be happy to answer.
+
+206
+00:16:40,000 --> 00:16:47,000
+Now, let's demo another thing I need to all to use a table one more time to demo you and not just sing.
+
+207
+00:16:48,000 --> 00:16:55,000
+Now, in certain key options, I'm going to select Cascade, what we expect now on that date.
+
+208
+00:16:55,000 --> 00:16:58,000
+Foreign key should be updated on remove.
+
+209
+00:16:58,000 --> 00:17:00,000
+Related records will be removed.
+
+210
+00:17:01,000 --> 00:17:06,000
+Let's get back to the table in his updated primary key for one record.
+
+211
+00:17:07,000 --> 00:17:09,000
+It will be updated in another table.
+
+212
+00:17:13,000 --> 00:17:15,000
+Let me open user table now.
+
+213
+00:17:16,000 --> 00:17:21,000
+You also can see that foreign key has been changed once I refreshed table.
+
+214
+00:17:22,000 --> 00:17:28,000
+So refresh table, you need to execute select queries, it was prepared by my school workbench one more
+
+215
+00:17:28,000 --> 00:17:28,000
+time.
+
+216
+00:17:29,000 --> 00:17:34,000
+Let me open the roll table again and let me remove zero plays its role.
+
+217
+00:17:35,000 --> 00:17:39,000
+I execute this query, no error so far.
+
+218
+00:17:39,000 --> 00:17:46,000
+And once this query is executed and Temple is removed from parent table with triggered cascading operation
+
+219
+00:17:46,000 --> 00:17:49,000
+in a related table on the delete event.
+
+220
+00:17:49,000 --> 00:17:53,000
+All related rows should be also removed in cascade cascading manner.
+
+221
+00:17:54,000 --> 00:17:59,000
+Let me refresh your user table and you can see that throws the reference to the tackles that we have
+
+222
+00:17:59,000 --> 00:18:01,000
+just removed is also removed.
+
+223
+00:18:02,000 --> 00:18:04,000
+Let's adjust foreign key constraint.
+
+224
+00:18:04,000 --> 00:18:07,000
+And this time we'll select said no.
+
+225
+00:18:13,000 --> 00:18:15,000
+Once we apply, it all changes.
+
+226
+00:18:15,000 --> 00:18:22,000
+I assume you can understand what will happen in case a remove role in parent table or update primer
+
+227
+00:18:22,000 --> 00:18:26,000
+key Zen related values in foreign key will be set up.
+
+228
+00:18:27,000 --> 00:18:33,000
+That's all possible because current operations is that you can perform in my school in tables was not
+
+229
+00:18:33,000 --> 00:18:34,000
+in the engine.
+
+230
+00:18:34,000 --> 00:18:35,000
+I don't know them.
+
+231
+00:18:35,000 --> 00:18:38,000
+You last for restrictions at the schools.
+
+232
+00:18:38,000 --> 00:18:43,000
+No action because I assume you are smart enough to understand what will happen.
+
+233
+00:18:44,000 --> 00:18:50,000
+And if you want to remove foreign key constraint, just open table configurations by selecting all the
+
+234
+00:18:50,000 --> 00:18:57,000
+table one more time and click the lead, select it on the foreign key constraint and take the kids query.
+
+235
+00:18:57,000 --> 00:18:58,000
+That's it.
+
+236
+00:18:59,000 --> 00:19:05,000
+On this example, I believe you already understood what data, consistency and data validity means.
+
+237
+00:19:06,000 --> 00:19:11,000
+In other words, this is nothing more than referential integrity and internal consistency.
+
+238
+00:19:12,000 --> 00:19:19,000
+Data consistency means that there is consistency in measurement of variables throughout data sets.
+
+239
+00:19:20,000 --> 00:19:28,000
+Data integrity is the overall accuracy and consistency of data and database can be set to be data consistent.
+
+240
+00:19:28,000 --> 00:19:36,000
+Once the content and the question doesn't give us a chance to infer a contradiction directly or indirectly,
+
+241
+00:19:37,000 --> 00:19:41,000
+data can be entirely consistent, but entirely wrong.
+
+242
+00:19:41,000 --> 00:19:46,000
+So the phrase data integrity is about the quality of data.
+
+243
+00:19:46,000 --> 00:19:53,000
+Database management systems provide data consistency tools, which can help around data integrity.
+
+244
+00:19:54,000 --> 00:20:00,000
+These are the parameters which are used to indicate the condition of data, such as data quality.
+
+245
+00:20:01,000 --> 00:20:04,000
+Data quality is a measurement of the condition of data.
+
+246
+00:20:04,000 --> 00:20:12,000
+Considering factors such as accuracy, completeness, consistency, data integrity is not about data
+
+247
+00:20:12,000 --> 00:20:13,000
+quality.
+
+248
+00:20:13,000 --> 00:20:20,000
+Data quality answer some questions, such as meetings or defined standards of an organization.
+
+249
+00:20:20,000 --> 00:20:23,000
+Data quality is a part of data integrity.
+
+250
+00:20:24,000 --> 00:20:32,000
+Data integrity includes all aspects of data quality and also force rules and includes review one more
+
+251
+00:20:32,000 --> 00:20:34,000
+term like data validity.
+
+252
+00:20:35,000 --> 00:20:41,000
+It is worth to say that this is just an aspect of data quality consistent in its settings.
+
+253
+00:20:41,000 --> 00:20:46,000
+This is a natural process of data obsolescence increase in time.
+
+254
+00:20:47,000 --> 00:20:48,000
+Stay tuned.
+
+255
+00:20:48,000 --> 00:20:54,000
+We'll have a lot of lessons where we'll discuss tools and techniques to ensure the best data quality.
+
+256
+00:20:54,000 --> 00:20:56,000
+That's all for this lesson.
+
+257
+00:20:56,000 --> 00:21:03,000
+Let's recap what we have learned today in this lesson, we have learned what referential integrity is
+
+258
+00:21:03,000 --> 00:21:04,000
+now.
+
+259
+00:21:04,000 --> 00:21:07,000
+You know what consequences of broken, referential integrity are.
+
+260
+00:21:08,000 --> 00:21:13,000
+We learned the concept of cascading operations and practice activities.
+
+261
+00:21:13,000 --> 00:21:16,000
+We can figure foreign key constraint in our tables.
+
+262
+00:21:16,000 --> 00:21:22,000
+I am sure that after this lesson, you have a clear understanding of what data consistency, data integrity,
+
+263
+00:21:23,000 --> 00:21:25,000
+data quality and data related to is.
+
+264
+00:21:26,000 --> 00:21:27,000
+Thanks a lot for your attention.
+
+265
+00:21:28,000 --> 00:21:29,000
+Have a great day.
+
+266
+00:21:29,000 --> 00:21:31,000
+See you in the next lesson.
+

47 - Relational databases/004 Indexes in Databases_en.srt

@@ -0,0 +1,988 @@
+1
+00:00:05,000 --> 00:00:06,000
+Hello.
+
+2
+00:00:06,000 --> 00:00:10,000
+Yes, tenants in this lesson, we're going to learn indexes and databases.
+
+3
+00:00:10,000 --> 00:00:13,000
+I will explain you what they are and why we need them.
+
+4
+00:00:14,000 --> 00:00:16,000
+Also, we'll have practiced during the lesson.
+
+5
+00:00:16,000 --> 00:00:22,000
+We'll create a few indexes for our existing tables that we created in previous videos.
+
+6
+00:00:23,000 --> 00:00:28,000
+In the lesson, we're going to learn definition of index, and I will explain you what it is.
+
+7
+00:00:28,000 --> 00:00:32,000
+One example you're going to understand why we need indexes.
+
+8
+00:00:33,000 --> 00:00:40,000
+Also, we're going to give you a different index types Ziya primary, secondary and clustering.
+
+9
+00:00:41,000 --> 00:00:45,000
+Also, we're going to have a practice during the lesson in my school workbench.
+
+10
+00:00:45,000 --> 00:00:51,000
+We're going to learn how to create indexes kind of figures, work with different properties and delays.
+
+11
+00:00:52,000 --> 00:00:58,000
+And as a summary, at the end of the lesson, we're going to review advantages and disadvantages of
+
+12
+00:00:58,000 --> 00:00:59,000
+using indexes.
+
+13
+00:01:00,000 --> 00:01:01,000
+Let's start our lesson.
+
+14
+00:01:02,000 --> 00:01:10,000
+We're going to start our lesson with definition of indexes, so what indexes indexes, the data structures,
+
+15
+00:01:10,000 --> 00:01:17,000
+it improves the speed of data retrieval operations on a database table and the cost of additional rights
+
+16
+00:01:17,000 --> 00:01:18,000
+and storage space.
+
+17
+00:01:19,000 --> 00:01:21,000
+The main things are index data structure.
+
+18
+00:01:22,000 --> 00:01:28,000
+Indexes are used to quickly allocate data without having to search every row in a database table.
+
+19
+00:01:28,000 --> 00:01:31,000
+Every time and database table is accessed.
+
+20
+00:01:32,000 --> 00:01:40,000
+Indexes can be created using one or more columns of a database table provides a basis for both rapid
+
+21
+00:01:40,000 --> 00:01:47,000
+random lookups, and the efficient access of order records in the minutes will explain what lookups
+
+22
+00:01:47,000 --> 00:01:49,000
+are then distant.
+
+23
+00:01:49,000 --> 00:01:50,000
+What is an index?
+
+24
+00:01:51,000 --> 00:01:56,000
+In most simple words, and index is a small table having only two columns.
+
+25
+00:01:56,000 --> 00:02:00,000
+The first column is a copy of the primary key off a table.
+
+26
+00:02:00,000 --> 00:02:08,000
+The second column contains a set of pointers for holding the address of the disk block, whereas it's
+
+27
+00:02:08,000 --> 00:02:10,000
+specific related to accurate is stored.
+
+28
+00:02:11,000 --> 00:02:14,000
+In some cases, index is sorted and extracted.
+
+29
+00:02:14,000 --> 00:02:18,000
+The reference to the records become easier thing to do.
+
+30
+00:02:18,000 --> 00:02:23,000
+An operation is significantly faster rather than going over each row.
+
+31
+00:02:24,000 --> 00:02:28,000
+Before we move further was none of indexes in details.
+
+32
+00:02:28,000 --> 00:02:34,000
+I promised you to explain what lookup tables are in computer science.
+
+33
+00:02:34,000 --> 00:02:41,000
+A lookup table isn't the rate that replaces runtime computation with a simpler rate indexing operation.
+
+34
+00:02:42,000 --> 00:02:49,000
+The savings in processing time can be significant because retrieving a value from memory is often faster
+
+35
+00:02:49,000 --> 00:02:54,000
+than carrying out an expensive computation or input output operation.
+
+36
+00:02:55,000 --> 00:02:59,000
+The tables may be calculated and stored in static storage.
+
+37
+00:03:00,000 --> 00:03:06,000
+This assumption doesn't require for a separate lesson, but still important for you to know this chunk.
+
+38
+00:03:07,000 --> 00:03:14,000
+Sometimes you're going to create such lookup tables or just how easy called lookups in your database
+
+39
+00:03:15,000 --> 00:03:21,000
+and definitely indexing will help you significantly improve performance of your app by reducing the
+
+40
+00:03:21,000 --> 00:03:24,000
+time of computation to find the value you need.
+
+41
+00:03:25,000 --> 00:03:30,000
+That was a small step aside to make sure you understood all terms I mentioned.
+
+42
+00:03:31,000 --> 00:03:36,000
+Let's understand now in more detail what does indexing do and why?
+
+43
+00:03:36,000 --> 00:03:39,000
+It is important and deserves a separate lesson.
+
+44
+00:03:40,000 --> 00:03:47,000
+Indexing is a way to get an order table into an order that will maximize the query efficiency.
+
+45
+00:03:47,000 --> 00:03:55,000
+While searching one table is an index is the order of the rows will likely not to be discernable by
+
+46
+00:03:55,000 --> 00:04:03,000
+the query as optimized in any way, and your query will therefore have to search through the rows leniently.
+
+47
+00:04:03,000 --> 00:04:10,000
+In other words, the queries will have to search through every rule to find zeros matching the conditions.
+
+48
+00:04:11,000 --> 00:04:14,000
+As you can imagine, this can take a long time.
+
+49
+00:04:14,000 --> 00:04:18,000
+Looking through every single row is not very efficient.
+
+50
+00:04:18,000 --> 00:04:26,000
+Imagine that you have a list of users in your database and that 100000 of them and you need to find
+
+51
+00:04:26,000 --> 00:04:27,000
+the user by its email.
+
+52
+00:04:28,000 --> 00:04:34,000
+You can pass users email as a search query to a database, but to find zeros.
+
+53
+00:04:34,000 --> 00:04:36,000
+It's a unique database will go over each row.
+
+54
+00:04:36,000 --> 00:04:41,000
+Compare and email in a search query was the actual email in each table.
+
+55
+00:04:42,000 --> 00:04:45,000
+How much time will it take to iterate over each couple?
+
+56
+00:04:46,000 --> 00:04:46,000
+Would this soon?
+
+57
+00:04:47,000 --> 00:04:55,000
+Well, believe me, it will take time in the sense of post to improve the performance of the database
+
+58
+00:04:55,000 --> 00:05:00,000
+while reading data from an index causes the database to create a data structure.
+
+59
+00:05:01,000 --> 00:05:07,000
+In this data structure, with a search term and pointer to the actual records in the database, for
+
+60
+00:05:07,000 --> 00:05:11,000
+example, index can be created for email column.
+
+61
+00:05:11,000 --> 00:05:16,000
+In this case, index will consist from the email value and point that does.
+
+62
+00:05:16,000 --> 00:05:22,000
+A table associated with this email pointer is, simply speaking, the reference information for the
+
+63
+00:05:22,000 --> 00:05:26,000
+location of the additional information in memory.
+
+64
+00:05:26,000 --> 00:05:33,000
+Basically, the index holds is a search term and that particular rows home address on the memory disk
+
+65
+00:05:34,000 --> 00:05:41,000
+index records comprise such key values and data pointers, multilevel indexes, stores and the disk,
+
+66
+00:05:41,000 --> 00:05:43,000
+along with the actual database files.
+
+67
+00:05:44,000 --> 00:05:48,000
+As the size of the database grows, so does the size of the indexes.
+
+68
+00:05:49,000 --> 00:05:56,000
+There is an immense need to keep the index records in the main memory so as to speed up the search operations.
+
+69
+00:05:56,000 --> 00:06:03,000
+If single level indexes used in the large size index can not be kept in memory, which leads to multiple
+
+70
+00:06:03,000 --> 00:06:11,000
+disk accesses, Multilevel Index helps in breaking down the index into several smaller indexes in order
+
+71
+00:06:11,000 --> 00:06:18,000
+to make the outermost level so small that it can be saved in a single disk block, which can easily
+
+72
+00:06:18,000 --> 00:06:21,000
+be accommodated anywhere in the main memory.
+
+73
+00:06:22,000 --> 00:06:25,000
+The index data structure tarp is very likely and B three.
+
+74
+00:06:26,000 --> 00:06:26,000
+What is it?
+
+75
+00:06:27,000 --> 00:06:32,000
+In case you are not familiar with this kind of the destruction, I will briefly explain the main points
+
+76
+00:06:32,000 --> 00:06:32,000
+now.
+
+77
+00:06:33,000 --> 00:06:35,000
+Well, the advantage of the big three are numerous.
+
+78
+00:06:36,000 --> 00:06:42,000
+The main advantage for our purposes is that it is searchable when the data structure is sorted in order.
+
+79
+00:06:42,000 --> 00:06:45,000
+It makes our search more efficient for obvious reasons.
+
+80
+00:06:46,000 --> 00:06:53,000
+So the definition of victory sounds like this mitre is a self-balancing tree data structure that maintains
+
+81
+00:06:53,000 --> 00:06:55,000
+source data and allows searches.
+
+82
+00:06:56,000 --> 00:07:04,000
+Sequential access insertions and deletions in logarithmic time and arbitrary is a balanced binary search
+
+83
+00:07:04,000 --> 00:07:07,000
+tree that follows a multilevel index format.
+
+84
+00:07:07,000 --> 00:07:11,000
+The leaf nodes of a tree denote actual data point.
+
+85
+00:07:11,000 --> 00:07:17,000
+This V3 ensures that all leaf must remain as the same height.
+
+86
+00:07:17,000 --> 00:07:18,000
+Thus, balance.
+
+87
+00:07:19,000 --> 00:07:23,000
+Additionally, the leaf nodes are linked using Eliquis.
+
+88
+00:07:24,000 --> 00:07:29,000
+Therefore, Arbitrary can support random access as well as sequential access.
+
+89
+00:07:30,000 --> 00:07:35,000
+If you want to run this data structure in details, I have a course where I reviewed different data
+
+90
+00:07:35,000 --> 00:07:38,000
+structures on examples of containers in Java.
+
+91
+00:07:39,000 --> 00:07:40,000
+But the general idea is the same.
+
+92
+00:07:41,000 --> 00:07:44,000
+You can check my Java Collections framework course if you wish.
+
+93
+00:07:45,000 --> 00:07:49,000
+I also explained in details would be connotation is in that course.
+
+94
+00:07:50,000 --> 00:07:53,000
+Now let's proceed with learning of indexes.
+
+95
+00:07:54,000 --> 00:07:58,000
+I'm going to explain in now different types of indexes the three types of Zen.
+
+96
+00:07:59,000 --> 00:08:07,000
+They are primary secondary clustering, primary index and turn maybe dance or sparse.
+
+97
+00:08:07,000 --> 00:08:14,000
+Primary index refers to an index stored in sorted order on the certain key of data storage and blocks
+
+98
+00:08:15,000 --> 00:08:16,000
+to look up a value.
+
+99
+00:08:17,000 --> 00:08:23,000
+You do a binary search on the index, which will produce a pointer to the blog, and then you can do
+
+100
+00:08:23,000 --> 00:08:26,000
+a binary search on the data in the block.
+
+101
+00:08:26,000 --> 00:08:28,000
+Let's start from the primary index.
+
+102
+00:08:29,000 --> 00:08:35,000
+Primary indexes and orders file, which is fixed length size, which still feels and like we have previously
+
+103
+00:08:35,000 --> 00:08:36,000
+discussed.
+
+104
+00:08:36,000 --> 00:08:43,000
+The first field is the same as index value, and second is a pointer to that specific data block.
+
+105
+00:08:43,000 --> 00:08:50,000
+We can say that there is always one to one relationship between the entries in the index table you already
+
+106
+00:08:50,000 --> 00:08:52,000
+know from previous slide.
+
+107
+00:08:52,000 --> 00:09:00,000
+The primary index member is a dense or sparse and dense indexing database is an index was pairs of keys
+
+108
+00:09:00,000 --> 00:09:02,000
+and pointers for every records.
+
+109
+00:09:02,000 --> 00:09:08,000
+Every key in this file is associated with a particular point that the record in the source of data file.
+
+110
+00:09:09,000 --> 00:09:15,000
+This means that the number of records in the index table is the same as the number of records in the
+
+111
+00:09:15,000 --> 00:09:16,000
+main table.
+
+112
+00:09:17,000 --> 00:09:24,000
+Obviously, this type of index needs more space to store index records itself in comparison with sparse
+
+113
+00:09:24,000 --> 00:09:25,000
+primary index.
+
+114
+00:09:26,000 --> 00:09:29,000
+The Spurs primary index is somewhat different.
+
+115
+00:09:29,000 --> 00:09:34,000
+It is an index record that appears for only some of the values in the file.
+
+116
+00:09:35,000 --> 00:09:41,000
+Sparse Index helps you to resolve the issues of dense index and database management system.
+
+117
+00:09:42,000 --> 00:09:49,000
+Following this indexing technique, a range of index columns stores the same data block address, and
+
+118
+00:09:49,000 --> 00:09:53,000
+when data needs to be retrieved, the block address will be fetched.
+
+119
+00:09:54,000 --> 00:09:57,000
+This is key difference between dance and sports in this.
+
+120
+00:09:58,000 --> 00:10:03,000
+Let me repeat one more time, in other words, and pay attention to the visualisation of the slide.
+
+121
+00:10:03,000 --> 00:10:07,000
+To understand this better, we have blocks that source.
+
+122
+00:10:07,000 --> 00:10:15,000
+A range of data is a clear and based on the search query, I get access to the block of data.
+
+123
+00:10:16,000 --> 00:10:20,000
+After that, we'll go over the data and look linearly till we get the requested data.
+
+124
+00:10:21,000 --> 00:10:28,000
+Also, in comparison to dancing, surpassing the source index records for only some search key values.
+
+125
+00:10:28,000 --> 00:10:35,000
+Thus, its advantage in requiring less space, less maintenance overhead for insertion and deletions.
+
+126
+00:10:36,000 --> 00:10:40,000
+So as you already understood, sparse index is called.
+
+127
+00:10:40,000 --> 00:10:47,000
+So because we need less number of pointers from index, the records of database all records are arranged
+
+128
+00:10:47,000 --> 00:10:55,000
+based on order is key, and hence we can quickly access the record by going to block first and then
+
+129
+00:10:55,000 --> 00:11:00,000
+access the following records without having individual index for each of the records.
+
+130
+00:11:00,000 --> 00:11:01,000
+Does it make sense?
+
+131
+00:11:02,000 --> 00:11:08,000
+We are done with primary in this, even in case you have any questions related to primary index.
+
+132
+00:11:08,000 --> 00:11:15,000
+Please do not hesitate to ask your questions in the comments to this video, and I will be happy to
+
+133
+00:11:15,000 --> 00:11:15,000
+answer.
+
+134
+00:11:16,000 --> 00:11:18,000
+Let's move on now.
+
+135
+00:11:18,000 --> 00:11:20,000
+Let's discuss and learn what secondary indexes.
+
+136
+00:11:21,000 --> 00:11:28,000
+In the index in database management system can be generated by a field which has a unique value for
+
+137
+00:11:28,000 --> 00:11:31,000
+each record, and it should be a candidate key.
+
+138
+00:11:32,000 --> 00:11:38,000
+If you don't remember what candidate K is this similar turn to alternate key?
+
+139
+00:11:38,000 --> 00:11:43,000
+Please review one more time lesson about basic terms in a relational databases.
+
+140
+00:11:44,000 --> 00:11:51,000
+Imagine that you have a table of users, and most likely you're going to have a column that will be
+
+141
+00:11:51,000 --> 00:11:55,000
+used as primary key and primary index for records in this table.
+
+142
+00:11:56,000 --> 00:12:02,000
+But you know that according to your business, logic user may be often requested by email.
+
+143
+00:12:03,000 --> 00:12:06,000
+That's why you decide to create one more index for email.
+
+144
+00:12:07,000 --> 00:12:13,000
+Email column contains also unique values and may be treated as candidate key.
+
+145
+00:12:13,000 --> 00:12:14,000
+Does it make sense?
+
+146
+00:12:15,000 --> 00:12:16,000
+Let me explain now.
+
+147
+00:12:16,000 --> 00:12:24,000
+Cluster Index If you all understood what's primary and secondary indexes are, it will be easier for
+
+148
+00:12:24,000 --> 00:12:26,000
+you to understand clustering index.
+
+149
+00:12:27,000 --> 00:12:33,000
+Imagine that you want to improve performance of reading the records, querying them by column that may
+
+150
+00:12:33,000 --> 00:12:35,000
+contain similar values and multiple rows.
+
+151
+00:12:36,000 --> 00:12:42,000
+For example, in the same scenario with users, in case you want to search user by their last name,
+
+152
+00:12:43,000 --> 00:12:47,000
+you should understand is it last name may not always be unique.
+
+153
+00:12:48,000 --> 00:12:56,000
+Z.Z Use Case of Clustering Index In order to identify the records first, it will look two or more columns
+
+154
+00:12:56,000 --> 00:13:00,000
+together to get the values and create index out of them.
+
+155
+00:13:00,000 --> 00:13:06,000
+Pay attention to this because it is critically important to have unique search query, and this is impossible
+
+156
+00:13:06,000 --> 00:13:09,000
+to create index on non unique values.
+
+157
+00:13:10,000 --> 00:13:16,000
+So you still would need to identify a combination of columns that will give you Zanik value for each
+
+158
+00:13:16,000 --> 00:13:19,000
+step and create index based on that.
+
+159
+00:13:19,000 --> 00:13:26,000
+This method is called a clustering index, basically records with similar characteristics and grouped
+
+160
+00:13:26,000 --> 00:13:29,000
+together, and indexes are created for these groups.
+
+161
+00:13:30,000 --> 00:13:34,000
+I believe they learned enough theory to jump the practice activities.
+
+162
+00:13:35,000 --> 00:13:39,000
+We're going to use our user tables that we created in previous lessons.
+
+163
+00:13:39,000 --> 00:13:42,000
+In case you don't know how to create a table.
+
+164
+00:13:42,000 --> 00:13:43,000
+Want to create a similar one?
+
+165
+00:13:44,000 --> 00:13:46,000
+Please make sure you watch the previous lesson.
+
+166
+00:13:47,000 --> 00:13:53,000
+When we created our first table and database do mouse, right click over the table and select Alter
+
+167
+00:13:53,000 --> 00:13:57,000
+Table Select Indexes set up here.
+
+168
+00:13:58,000 --> 00:14:03,000
+This is a tab that allows us to create, configure and remove indexes.
+
+169
+00:14:04,000 --> 00:14:11,000
+Each index has name to create new index, click in an empty row and time and a name.
+
+170
+00:14:11,000 --> 00:14:13,000
+After that, select in the start.
+
+171
+00:14:14,000 --> 00:14:16,000
+Let me review Is you each of this?
+
+172
+00:14:17,000 --> 00:14:18,000
+This is my SQL index types.
+
+173
+00:14:19,000 --> 00:14:26,000
+They're similar from the relational database theory that we have discussed, but definitely this ones
+
+174
+00:14:26,000 --> 00:14:29,000
+have specifics related to my school database management system.
+
+175
+00:14:29,000 --> 00:14:37,000
+Only primary index is created by default for each primary key, and you see the one was already created.
+
+176
+00:14:38,000 --> 00:14:42,000
+My school creates the index by default for primary key column.
+
+177
+00:14:43,000 --> 00:14:46,000
+You can click on existing index to explore the details.
+
+178
+00:14:47,000 --> 00:14:55,000
+For example, you can learn which column is used to create this index and column, or I send them all
+
+179
+00:14:55,000 --> 00:14:55,000
+this send.
+
+180
+00:14:56,000 --> 00:15:04,000
+In this time may be used for secondary indexes, that means that values in this column may not be unique.
+
+181
+00:15:05,000 --> 00:15:10,000
+For example, you can see that my school automatically created index for foreign key.
+
+182
+00:15:11,000 --> 00:15:12,000
+I didn't do that.
+
+183
+00:15:12,000 --> 00:15:14,000
+This was done by my school.
+
+184
+00:15:15,000 --> 00:15:19,000
+Unique index type created four columns was only unique values.
+
+185
+00:15:20,000 --> 00:15:24,000
+For example, you may have unique properties set for email column.
+
+186
+00:15:24,000 --> 00:15:28,000
+That means that it is possible to create unique index for this column.
+
+187
+00:15:28,000 --> 00:15:32,000
+To discuss reading operations from user table.
+
+188
+00:15:32,000 --> 00:15:36,000
+Using user email in search query will become faster.
+
+189
+00:15:36,000 --> 00:15:44,000
+Full text indexes are used for full text searches on in the BE and might use some storage engines,
+
+190
+00:15:44,000 --> 00:15:50,000
+support full text indexes and only for Char Bircher and text columns.
+
+191
+00:15:51,000 --> 00:15:56,000
+Indexing always takes place over the entire column and column preface.
+
+192
+00:15:57,000 --> 00:16:01,000
+Also, we can create indexes on spatial data types.
+
+193
+00:16:01,000 --> 00:16:10,000
+My Esam and in B supports our three indexes on special types as a search engines use matrix for index
+
+194
+00:16:10,000 --> 00:16:17,000
+and special types, except for archive, which doesn't support special type indexing.
+
+195
+00:16:19,000 --> 00:16:25,000
+On this slide, you can see the characteristics of different index types in energy B storage engine
+
+196
+00:16:25,000 --> 00:16:26,000
+of my school.
+
+197
+00:16:27,000 --> 00:16:31,000
+Each index also has a different set of properties.
+
+198
+00:16:31,000 --> 00:16:38,000
+Let's review each of them for string columns, indexes may use only as a leading part of column values
+
+199
+00:16:39,000 --> 00:16:40,000
+using blanks property.
+
+200
+00:16:41,000 --> 00:16:47,000
+This allows us to create index only for prefixes and other properties that can be used.
+
+201
+00:16:47,000 --> 00:16:55,000
+Here is a key block source for my use some tables Key block size optionally specifies the size in bytes
+
+202
+00:16:55,000 --> 00:16:57,000
+to use for index key blocks.
+
+203
+00:16:58,000 --> 00:17:03,000
+The value is treated as a hint and different size could be used if necessary.
+
+204
+00:17:04,000 --> 00:17:10,000
+Akeem Look Source value specified for an individual index definition overrides a table level key block
+
+205
+00:17:10,000 --> 00:17:11,000
+size value.
+
+206
+00:17:12,000 --> 00:17:15,000
+It is not supported at the index level for any DB tables.
+
+207
+00:17:16,000 --> 00:17:21,000
+Also only for full text indexes, you can specify parser.
+
+208
+00:17:22,000 --> 00:17:29,000
+It associates a person plug in with the index if full text indexing and search and operations need special
+
+209
+00:17:29,000 --> 00:17:34,000
+handling in London, B and My s some supports full text parser plugins.
+
+210
+00:17:34,000 --> 00:17:40,000
+If you are interested, you can find more information in official documentation of my SQL about full
+
+211
+00:17:40,000 --> 00:17:47,000
+text parser plugins for this specific case, I believe that topic lies outside of the scope of this
+
+212
+00:17:47,000 --> 00:17:48,000
+lesson.
+
+213
+00:17:48,000 --> 00:17:51,000
+Also, you can specify index visibility.
+
+214
+00:17:51,000 --> 00:17:53,000
+You have separate checkbox here.
+
+215
+00:17:54,000 --> 00:18:01,000
+You can place a tweak to make index visible and you can remove it take to make index invisible.
+
+216
+00:18:01,000 --> 00:18:04,000
+My cycle supports invisible indexes.
+
+217
+00:18:04,000 --> 00:18:08,000
+That is, indexes that are not used by the optimizer.
+
+218
+00:18:09,000 --> 00:18:13,000
+The feature applies to indexes, pauses and primary keys.
+
+219
+00:18:13,000 --> 00:18:18,000
+Using explicit or implicit indexes are visible by default.
+
+220
+00:18:19,000 --> 00:18:27,000
+After you configure it all what you need, just click apply button and execute generated SQL query to
+
+221
+00:18:27,000 --> 00:18:32,000
+remove indexes that you created, do most right click on the index and click Delete selected.
+
+222
+00:18:33,000 --> 00:18:33,000
+That's it.
+
+223
+00:18:34,000 --> 00:18:40,000
+By this moment in our lesson, I believe you already have both theoretical and practical understanding
+
+224
+00:18:40,000 --> 00:18:41,000
+of indexes.
+
+225
+00:18:42,000 --> 00:18:47,000
+And now we will be able to come up with advantages and disadvantages of indexes.
+
+226
+00:18:47,000 --> 00:18:48,000
+Together with me.
+
+227
+00:18:49,000 --> 00:18:55,000
+And one advantage advantages of indexing it is worth to mention the following once it helps to reduce
+
+228
+00:18:55,000 --> 00:19:02,000
+the total number of input output operations needed to retrieve that data offers faster search and retrieval
+
+229
+00:19:02,000 --> 00:19:03,000
+of data.
+
+230
+00:19:04,000 --> 00:19:10,000
+So we can say that performance of raid operations is increased and we shouldn't forget about the next
+
+231
+00:19:10,000 --> 00:19:19,000
+disadvantages additional disk memory space needed to store index decreased performance of write operations,
+
+232
+00:19:19,000 --> 00:19:27,000
+slower insert, update and delete operations because besides removal of trouble, it is also required
+
+233
+00:19:27,000 --> 00:19:30,000
+to recalculate index to keep it in sorted state.
+
+234
+00:19:31,000 --> 00:19:34,000
+That's all what I wanted to discuss with you today in this lesson.
+
+235
+00:19:34,000 --> 00:19:36,000
+Let's recap what we have learned today.
+
+236
+00:19:37,000 --> 00:19:41,000
+In this lesson, we have learned a lot of interesting things about indexes.
+
+237
+00:19:42,000 --> 00:19:44,000
+They learned what indexing database is.
+
+238
+00:19:45,000 --> 00:19:48,000
+I believe that you understood why we need indexes.
+
+239
+00:19:49,000 --> 00:19:54,000
+Also, I put separate focus on the details to help you understand how it works.
+
+240
+00:19:55,000 --> 00:20:03,000
+You also know what be tree data structure is and how logarithmic connotation of elements retrieval from
+
+241
+00:20:03,000 --> 00:20:07,000
+collection may be achieved via a view of different index types.
+
+242
+00:20:08,000 --> 00:20:11,000
+Those include primary secondary clustering.
+
+243
+00:20:11,000 --> 00:20:18,000
+I showed you how to create and remove indexes in database, and at the end of the lesson, we have reviewed
+
+244
+00:20:18,000 --> 00:20:21,000
+advantages and disadvantages of using indexes.
+
+245
+00:20:22,000 --> 00:20:23,000
+That's all for this lesson.
+
+246
+00:20:24,000 --> 00:20:26,000
+Thanks a lot for your attention, Tim.
+
+247
+00:20:26,000 --> 00:20:29,000
+Have a great day and see you in the next lesson.
+

47 - Relational databases/005 Database Normalization & Denormalization_en.srt

@@ -0,0 +1,1576 @@
+1
+00:00:06,000 --> 00:00:11,000
+Hello, yes, tenants in this lesson, we're going to learn more advanced concepts in the relational
+
+2
+00:00:11,000 --> 00:00:12,000
+databases.
+
+3
+00:00:12,000 --> 00:00:17,000
+We're going to talk about database normalization and normalization.
+
+4
+00:00:17,000 --> 00:00:20,000
+Believe me, this is a really important lesson.
+
+5
+00:00:20,000 --> 00:00:26,000
+And knowing the rules that I'm going to share with you in this lesson, you will be able to create scalable
+
+6
+00:00:26,000 --> 00:00:28,000
+database architecture.
+
+7
+00:00:28,000 --> 00:00:31,000
+And also, this will help you a lot in your career.
+
+8
+00:00:32,000 --> 00:00:37,000
+We are going to study the lesson from understanding of what data anomalies are.
+
+9
+00:00:38,000 --> 00:00:44,000
+I'm going to explain what insertion date and deletion anomaly is known as a problem.
+
+10
+00:00:44,000 --> 00:00:46,000
+We'll learn how to avoid it.
+
+11
+00:00:46,000 --> 00:00:53,000
+And after understanding of basics of dependency theory, we'll jump to our main topic today.
+
+12
+00:00:53,000 --> 00:00:59,000
+I'm talking about normalization and normal forms that we are going to review with examples.
+
+13
+00:00:59,000 --> 00:01:03,000
+Anthem's and obsolescent will discuss what the normalization is.
+
+14
+00:01:04,000 --> 00:01:05,000
+Let's start our lesson.
+
+15
+00:01:06,000 --> 00:01:12,000
+And before we even jump to discussion of what normalization is, let's understand what problem we have
+
+16
+00:01:12,000 --> 00:01:13,000
+learned to address.
+
+17
+00:01:13,000 --> 00:01:16,000
+Let me explain you what data anomalies are.
+
+18
+00:01:17,000 --> 00:01:24,000
+Data anomalies are inconsistencies in the data stored in the database as a result of an operation such
+
+19
+00:01:24,000 --> 00:01:27,000
+as update insertion and or deletion.
+
+20
+00:01:28,000 --> 00:01:34,000
+Such inconsistencies may arise when we have a particular records stored in multiple locations, and
+
+21
+00:01:34,000 --> 00:01:42,000
+not all of the corpus are updated generally and with relational database design must capture all of
+
+22
+00:01:42,000 --> 00:01:45,000
+the necessary attributes and associations.
+
+23
+00:01:46,000 --> 00:01:53,000
+The design should do this was a minimal amount of storage information and no redundant data in database
+
+24
+00:01:53,000 --> 00:01:54,000
+design.
+
+25
+00:01:54,000 --> 00:02:01,000
+Redundancy is generally undesirable because it causes problems maintaining consistency after updates.
+
+26
+00:02:02,000 --> 00:02:08,000
+We are going to learn such term as normalization later today, but I already can say that normalization
+
+27
+00:02:08,000 --> 00:02:14,000
+can help us to reduce data redundancy and minimize risks of data anomalies.
+
+28
+00:02:14,000 --> 00:02:18,000
+But sometimes we want to add data redundancy on purpose.
+
+29
+00:02:19,000 --> 00:02:26,000
+We need to do this carefully and was clear understanding of why we are doing this and what benefits
+
+30
+00:02:26,000 --> 00:02:27,000
+we expect to get.
+
+31
+00:02:28,000 --> 00:02:31,000
+Redundancy can sometimes leave the performance improvements.
+
+32
+00:02:32,000 --> 00:02:36,000
+We are going to discuss how this may improve our performance.
+
+33
+00:02:36,000 --> 00:02:41,000
+One will talk about the normalization Xen different, anomalous.
+
+34
+00:02:41,000 --> 00:02:42,000
+Let's review some of them.
+
+35
+00:02:43,000 --> 00:02:47,000
+I'm going to show different types of anomalies on example.
+
+36
+00:02:47,000 --> 00:02:49,000
+Let's look at this example first.
+
+37
+00:02:50,000 --> 00:02:53,000
+Imagine that we have a table with suppliers.
+
+38
+00:02:53,000 --> 00:02:59,000
+We also store information about them like address and products they produce.
+
+39
+00:02:59,000 --> 00:03:04,000
+There is also information about quantity of each product and its price.
+
+40
+00:03:04,000 --> 00:03:05,000
+Is that clear?
+
+41
+00:03:06,000 --> 00:03:08,000
+What do you think about this table?
+
+42
+00:03:08,000 --> 00:03:10,000
+Is it looks good to you.
+
+43
+00:03:11,000 --> 00:03:17,000
+Well, we're going to review in detail what is wrong in such kind of tables.
+
+44
+00:03:17,000 --> 00:03:20,000
+You already see huge data redundancy in this table.
+
+45
+00:03:21,000 --> 00:03:27,000
+Also, I believe we can notice is that the relationships between a key attribute and other data you
+
+46
+00:03:27,000 --> 00:03:29,000
+topple is not always logical.
+
+47
+00:03:30,000 --> 00:03:34,000
+Let me show you in detail what problems may be caused by this data redundancy.
+
+48
+00:03:35,000 --> 00:03:42,000
+And the first anomalies that we are going to learn is insertion anomaly imagines that we need that new
+
+49
+00:03:42,000 --> 00:03:42,000
+supplier.
+
+50
+00:03:43,000 --> 00:03:45,000
+We know its name.
+
+51
+00:03:45,000 --> 00:03:49,000
+We know it's address, but we don't know.
+
+52
+00:03:49,000 --> 00:03:51,000
+These are products that it produces.
+
+53
+00:03:51,000 --> 00:03:53,000
+No prices for these brothers.
+
+54
+00:03:53,000 --> 00:03:56,000
+We just started cooperation with them.
+
+55
+00:03:56,000 --> 00:03:58,000
+A company has been just registered.
+
+56
+00:03:59,000 --> 00:04:03,000
+And what should I put in product quantity and price columns?
+
+57
+00:04:03,000 --> 00:04:06,000
+I have to put empty, of course, data.
+
+58
+00:04:06,000 --> 00:04:09,000
+In this case, I have to base is a No.
+
+59
+00:04:10,000 --> 00:04:12,000
+Zero in different columns.
+
+60
+00:04:12,000 --> 00:04:13,000
+But is this correct?
+
+61
+00:04:14,000 --> 00:04:21,000
+Why I obligated to come up with values for columns that I don't need to use in this moment?
+
+62
+00:04:21,000 --> 00:04:29,000
+What if I just not aware about their products or why after companies established that was information
+
+63
+00:04:29,000 --> 00:04:30,000
+about their products?
+
+64
+00:04:30,000 --> 00:04:35,000
+If I just could add new rows was a product a lot of questions.
+
+65
+00:04:36,000 --> 00:04:42,000
+Another type of anomaly is update anomaly imagines that we decided to update supplier name.
+
+66
+00:04:43,000 --> 00:04:48,000
+Probably because of company reorganization, they decided to change their public name.
+
+67
+00:04:49,000 --> 00:04:56,000
+And now we need to execute the query to update all tables where we used suppliers name.
+
+68
+00:04:56,000 --> 00:05:01,000
+And we have really a lot of records where we need to accommodate supplier snake.
+
+69
+00:05:02,000 --> 00:05:10,000
+But what if we accidentally forgot it for some records during insertion, we added out, and for some
+
+70
+00:05:10,000 --> 00:05:10,000
+not.
+
+71
+00:05:11,000 --> 00:05:18,000
+What if accidentally SSEG different amount of space characters and some records still will be not updated?
+
+72
+00:05:18,000 --> 00:05:26,000
+In this case, I'm going to face that anomaly because after object, I will have inconsistent and not
+
+73
+00:05:26,000 --> 00:05:27,000
+valid data.
+
+74
+00:05:28,000 --> 00:05:30,000
+Do not accidentally forget the date throws.
+
+75
+00:05:30,000 --> 00:05:38,000
+It would be better if we could organize the restructure in a way when we have only one place where we
+
+76
+00:05:38,000 --> 00:05:43,000
+store supplier's name, then the risk of facing an added anomaly is minimal.
+
+77
+00:05:44,000 --> 00:05:46,000
+Let's have the deletion anomaly now.
+
+78
+00:05:47,000 --> 00:05:54,000
+This type of anomaly may occur when we remove information and together with it, or remove information
+
+79
+00:05:54,000 --> 00:05:55,000
+that shouldn't be removed.
+
+80
+00:05:56,000 --> 00:06:04,000
+For example, we stopped cooperation with one supplier or we need just to remove information about delivery.
+
+81
+00:06:04,000 --> 00:06:11,000
+And in case we remove information about delivery, we lose information about our supplier and vice versa.
+
+82
+00:06:12,000 --> 00:06:15,000
+All this information is important for our accounting department.
+
+83
+00:06:16,000 --> 00:06:20,000
+We also might need to use this information to create different reports.
+
+84
+00:06:21,000 --> 00:06:25,000
+What we should do in this case, it is hard question to answer.
+
+85
+00:06:26,000 --> 00:06:30,000
+Do you see what problems may be caused by data redundancy in our table?
+
+86
+00:06:30,000 --> 00:06:32,000
+How to fix this.
+
+87
+00:06:32,000 --> 00:06:39,000
+The best approach to create tables without anomalies is to ensure that the tables are normalized, and
+
+88
+00:06:39,000 --> 00:06:43,000
+that's accomplished by understanding functional dependencies.
+
+89
+00:06:43,000 --> 00:06:49,000
+Functional dependency ensures that all attributes in the table belong to that table.
+
+90
+00:06:50,000 --> 00:06:54,000
+In other words, it will eliminate redundancies and anomalies.
+
+91
+00:06:55,000 --> 00:07:02,000
+Let me show you as a solution for our example and what structure would help us to avoid the two anomalies.
+
+92
+00:07:02,000 --> 00:07:07,000
+Let's change our tables and create two tables instead of one.
+
+93
+00:07:08,000 --> 00:07:12,000
+We create supply a table and also a great delivery table.
+
+94
+00:07:13,000 --> 00:07:17,000
+In one table, we can store all information related to supply.
+
+95
+00:07:17,000 --> 00:07:23,000
+And in another table, we're going to store all information related to delivery.
+
+96
+00:07:23,000 --> 00:07:26,000
+And we establish relationships between these two tables.
+
+97
+00:07:27,000 --> 00:07:31,000
+So avoid data duplication, for example, for each delivery.
+
+98
+00:07:31,000 --> 00:07:33,000
+There is a specific supply.
+
+99
+00:07:33,000 --> 00:07:36,000
+Each supplier can have many deliveries.
+
+100
+00:07:37,000 --> 00:07:39,000
+Each delivery is provided by one supplier.
+
+101
+00:07:40,000 --> 00:07:45,000
+Is it clear we want to add information about is delivery or supply?
+
+102
+00:07:46,000 --> 00:07:52,000
+We are not obligated to add false information or information that we don't have in this moment.
+
+103
+00:07:53,000 --> 00:07:56,000
+No dummy values are needed during the insertion.
+
+104
+00:07:56,000 --> 00:08:04,000
+This resource, our insertion anomaly in the case, we want to add the name of supplier or its address.
+
+105
+00:08:04,000 --> 00:08:07,000
+We shouldn't do this in hundredths rose.
+
+106
+00:08:07,000 --> 00:08:14,000
+We do this in one place and the reference to the supply is still the same in delivery table in case
+
+107
+00:08:14,000 --> 00:08:19,000
+we want to remove information about delivery but don't want to remove information about supply.
+
+108
+00:08:20,000 --> 00:08:27,000
+We just do so we can do that both from delivery table without losing data from supply table.
+
+109
+00:08:27,000 --> 00:08:28,000
+Isn't this cool?
+
+110
+00:08:29,000 --> 00:08:35,000
+That's why, though, would this anomalous, you need to know what normalization is and its main rules.
+
+111
+00:08:36,000 --> 00:08:42,000
+But before starting to learn normal forms and normalization, we need to learn a little bit more theory
+
+112
+00:08:43,000 --> 00:08:49,000
+because you need to know at least some key concepts from dependencies theory in order you could understand
+
+113
+00:08:49,000 --> 00:08:57,000
+normalization dependency theory is a sub field of database theory, which status, implication and optimization
+
+114
+00:08:57,000 --> 00:09:02,000
+problems related to logical constraints, commonly called dependencies.
+
+115
+00:09:02,000 --> 00:09:10,000
+On that basis, the best known class of such dependencies are functional dependencies, which forms
+
+116
+00:09:10,000 --> 00:09:13,000
+the foundation of keys on database relations.
+
+117
+00:09:13,000 --> 00:09:18,000
+And in this lesson, we are going to review excerpts from dependency theory.
+
+118
+00:09:18,000 --> 00:09:19,000
+Let's start.
+
+119
+00:09:20,000 --> 00:09:26,000
+And as a result, you said one of the main concept in the theory is functional dependency.
+
+120
+00:09:27,000 --> 00:09:34,000
+Financial dependency tells us that if we have two attributes X and Y of some relationship, then wise
+
+121
+00:09:34,000 --> 00:09:45,000
+functional dependence on X if in any moment of time each X value matches, only one y value X is set
+
+122
+00:09:45,000 --> 00:09:47,000
+to functionally determine Y.
+
+123
+00:09:48,000 --> 00:09:54,000
+Functional dependency is a constraint between two sets of attributes in the relation from a database,
+
+124
+00:09:55,000 --> 00:10:03,000
+for example, bus number and last name of the person employee and his corporate email.
+
+125
+00:10:03,000 --> 00:10:10,000
+We can say that there is a functional dependency between these attributes is the determination of functional
+
+126
+00:10:10,000 --> 00:10:17,000
+dependencies is an important part of designing databases in a relational model and in database standardization
+
+127
+00:10:17,000 --> 00:10:19,000
+and generalization.
+
+128
+00:10:19,000 --> 00:10:26,000
+This is important to understand because during the normalization of our tables will investigate functional
+
+129
+00:10:26,000 --> 00:10:32,000
+dependencies between attributes, and it is crucial to identify which attributes that's in mind as the
+
+130
+00:10:32,000 --> 00:10:33,000
+ones.
+
+131
+00:10:34,000 --> 00:10:37,000
+Now, let's understand some more details.
+
+132
+00:10:37,000 --> 00:10:45,000
+Functional dependency between X and Y may be called complete functional dependency and Case Y is determined
+
+133
+00:10:45,000 --> 00:10:47,000
+by all subset of X.
+
+134
+00:10:47,000 --> 00:10:54,000
+And again, I'm trying to simplify these concepts as much as they can, because in cuz I would tell
+
+135
+00:10:54,000 --> 00:10:58,000
+you definition from Wikipedia, it wouldn't bring more sense.
+
+136
+00:10:59,000 --> 00:11:06,000
+For example, imagine that you have subsets of attributes like place of dispatch delivery, destination
+
+137
+00:11:06,000 --> 00:11:08,000
+type of cargo, cargo weight.
+
+138
+00:11:09,000 --> 00:11:12,000
+All these attributes determine price of delivery.
+
+139
+00:11:12,000 --> 00:11:13,000
+I agree.
+
+140
+00:11:14,000 --> 00:11:20,000
+You can easily check this by removing any attribute from the subset and check whether the relationship
+
+141
+00:11:20,000 --> 00:11:28,000
+is still valid because in case of cargo weight from subset of attributes, then the total price of delivery
+
+142
+00:11:28,000 --> 00:11:29,000
+will be completely different.
+
+143
+00:11:30,000 --> 00:11:36,000
+That's how easily I can check and ensure that there is complete functional dependency between set of
+
+144
+00:11:36,000 --> 00:11:38,000
+judgments and another attribute.
+
+145
+00:11:39,000 --> 00:11:39,000
+Does it make sense?
+
+146
+00:11:40,000 --> 00:11:46,000
+And last but not the least important thing I'd like you to know about functional dependency is clear
+
+147
+00:11:46,000 --> 00:11:49,000
+understanding of transitive dependency.
+
+148
+00:11:49,000 --> 00:11:50,000
+Let me explain.
+
+149
+00:11:51,000 --> 00:12:00,000
+Functional dependency X from Y may be called transitive if dependencies between X and Z and Z and Y,
+
+150
+00:12:01,000 --> 00:12:07,000
+but there is no direct dependency between X and Y, and this case dependency will be called transitive.
+
+151
+00:12:08,000 --> 00:12:14,000
+For example, there might be dependency between idea of employee and the DH of office, whereas this
+
+152
+00:12:14,000 --> 00:12:21,000
+employee works and there is another dependency between Officer NI and number of whom is that office.
+
+153
+00:12:22,000 --> 00:12:27,000
+So that means is a dependency between ideal employee and his office.
+
+154
+00:12:27,000 --> 00:12:28,000
+Phone number is transitive.
+
+155
+00:12:29,000 --> 00:12:29,000
+Is it clear?
+
+156
+00:12:31,000 --> 00:12:33,000
+Now, when we know what functional dependence it is.
+
+157
+00:12:33,000 --> 00:12:37,000
+Well, good to proceed with learning of normalization and normal forms.
+
+158
+00:12:38,000 --> 00:12:44,000
+Let's understand first what is normalization that at least normalization is a process of structure.
+
+159
+00:12:44,000 --> 00:12:52,000
+The database usually a relational database in accordance with serious of so-called normal forms in order
+
+160
+00:12:52,000 --> 00:12:56,000
+to reduce data redundancy and improve data integrity.
+
+161
+00:12:57,000 --> 00:13:02,000
+It was first proposed by Andrew Card as a part of his relational model.
+
+162
+00:13:03,000 --> 00:13:06,000
+That the definition of database normalization may sound like this.
+
+163
+00:13:07,000 --> 00:13:13,000
+Naming normalization is grouping and or distribution of attributes between different relationships to
+
+164
+00:13:13,000 --> 00:13:21,000
+eliminate data anomalies during their operations was database guarantee and data integrity and consistency
+
+165
+00:13:22,000 --> 00:13:23,000
+and optimization of DB.
+
+166
+00:13:24,000 --> 00:13:29,000
+In the definition of normalization, we use such term as normal forms.
+
+167
+00:13:30,000 --> 00:13:31,000
+What are normal forms?
+
+168
+00:13:32,000 --> 00:13:39,000
+A normal form is a property of a relationship in the relational data model that describes it from the
+
+169
+00:13:39,000 --> 00:13:45,000
+point of redundancy that can potentially lead to mistakes during the data insertion reading written
+
+170
+00:13:46,000 --> 00:13:47,000
+data deletion.
+
+171
+00:13:48,000 --> 00:13:54,000
+You already know about data anomalies and the other you saw examples based on this.
+
+172
+00:13:54,000 --> 00:13:59,000
+I make a conclusion that you understand our motivation to learn normal forms.
+
+173
+00:14:00,000 --> 00:14:02,000
+There are different normal forms.
+
+174
+00:14:02,000 --> 00:14:04,000
+We can say that three of them.
+
+175
+00:14:04,000 --> 00:14:05,000
+I mean, once.
+
+176
+00:14:06,000 --> 00:14:12,000
+But we also learn to hold an overview of different normal forms in this lesson to help you understand
+
+177
+00:14:12,000 --> 00:14:13,000
+this topic better.
+
+178
+00:14:14,000 --> 00:14:19,000
+We're going to review normal forms from the least normalized to most normalized.
+
+179
+00:14:20,000 --> 00:14:25,000
+In the other based harmonization and normalized form, it is also maybe referred as you, NF.
+
+180
+00:14:26,000 --> 00:14:31,000
+Also known as normalized relation or non first normal form.
+
+181
+00:14:31,000 --> 00:14:38,000
+This is a database data model which does meet any of the conditions of database normalization defined
+
+182
+00:14:38,000 --> 00:14:39,000
+by the relational model.
+
+183
+00:14:40,000 --> 00:14:48,000
+Database systems, which supports a normalized data, is sometimes called non relational or no SQL databases
+
+184
+00:14:48,000 --> 00:14:54,000
+in the relational model and normalized relations can be considered a starting point for a process of
+
+185
+00:14:54,000 --> 00:14:55,000
+normalization.
+
+186
+00:14:56,000 --> 00:15:02,000
+It should not be confused with the normalization when normalization is deliberately compromised for
+
+187
+00:15:02,000 --> 00:15:06,000
+selected tables in relational database normalization.
+
+188
+00:15:06,000 --> 00:15:12,000
+The first form requires initial data to be viewed as relations in database systems.
+
+189
+00:15:12,000 --> 00:15:14,000
+Relations are represented as tables.
+
+190
+00:15:15,000 --> 00:15:19,000
+The relation view implies some constraints on the tables.
+
+191
+00:15:20,000 --> 00:15:25,000
+No duplicates Ross Combs have unique names was in the same table.
+
+192
+00:15:25,000 --> 00:15:30,000
+Each column has data type, which defines allowed values in the column.
+
+193
+00:15:31,000 --> 00:15:34,000
+All rows in table have the same set of columns.
+
+194
+00:15:35,000 --> 00:15:36,000
+As you can see.
+
+195
+00:15:36,000 --> 00:15:40,000
+Most of the requirements are familiar to us and seems to be logical.
+
+196
+00:15:40,000 --> 00:15:46,000
+But from the theoretical point of view, this is just a starting point following normalization, and
+
+197
+00:15:46,000 --> 00:15:50,000
+the requirement is it should be mapped before we start applying even first normal form.
+
+198
+00:15:51,000 --> 00:15:54,000
+You can see an example of a normalized form on the slide.
+
+199
+00:15:55,000 --> 00:16:01,000
+This table represents a relation where transactions column is itself relation value.
+
+200
+00:16:01,000 --> 00:16:08,000
+This is relative relation but doesn't conform to first normal form, which doesn't allow nested relations.
+
+201
+00:16:09,000 --> 00:16:12,000
+The table is therefore a normalized.
+
+202
+00:16:12,000 --> 00:16:15,000
+If this is clear, then let's move on.
+
+203
+00:16:16,000 --> 00:16:19,000
+Let's see it was done in a basic normal form.
+
+204
+00:16:19,000 --> 00:16:23,000
+The first normal form relation is in the first normal form.
+
+205
+00:16:23,000 --> 00:16:32,000
+If and only if, no attribute domain has relations as elements or more informally, that no table column
+
+206
+00:16:32,000 --> 00:16:34,000
+can have tables as values.
+
+207
+00:16:35,000 --> 00:16:41,000
+But this definition tells us that the most relational databases already in the first normal form by
+
+208
+00:16:41,000 --> 00:16:45,000
+default because it is impossible to have table value in the relational database.
+
+209
+00:16:46,000 --> 00:16:50,000
+That's why I like another definition of the first normal form.
+
+210
+00:16:51,000 --> 00:16:58,000
+Relationship is in first normal form if and only if each its attribute is atomic.
+
+211
+00:16:58,000 --> 00:16:59,000
+What does it mean?
+
+212
+00:17:00,000 --> 00:17:01,000
+I told me catching it.
+
+213
+00:17:02,000 --> 00:17:08,000
+This means that in your business, to me and in business logic of application, there is no need to
+
+214
+00:17:08,000 --> 00:17:13,000
+extract on the specific parts of the attribute to perform some operation, was it?
+
+215
+00:17:14,000 --> 00:17:16,000
+Let me explain, is this on the example?
+
+216
+00:17:17,000 --> 00:17:21,000
+Imagine that you have supply a table and each supplier has its legal address.
+
+217
+00:17:22,000 --> 00:17:28,000
+This address contains Country City Street Building Office Number.
+
+218
+00:17:28,000 --> 00:17:35,000
+But what if your application needs to perform operations with suppliers based on their country location?
+
+219
+00:17:36,000 --> 00:17:43,000
+You need to be able to extract all supplies from Russia or all suppliers from India or Ukraine.
+
+220
+00:17:43,000 --> 00:17:47,000
+Or you say how you can do this with this data model.
+
+221
+00:17:48,000 --> 00:17:55,000
+The only way for you to do this is to extract as a whole address, then pass it inside the program and
+
+222
+00:17:55,000 --> 00:17:57,000
+take on the country well.
+
+223
+00:17:57,000 --> 00:18:02,000
+That's why we can say that this table violates the first normal form.
+
+224
+00:18:03,000 --> 00:18:06,000
+Domains are stable, meet requirements of the first normal form.
+
+225
+00:18:07,000 --> 00:18:09,000
+We need to introduce new columns in the table.
+
+226
+00:18:10,000 --> 00:18:16,000
+Let's have separate columns for country city street building and office number.
+
+227
+00:18:16,000 --> 00:18:22,000
+In this case, even when we need to extract suppliers for a specific city, we can do this easily by
+
+228
+00:18:22,000 --> 00:18:25,000
+using city attributes as a search parameter.
+
+229
+00:18:25,000 --> 00:18:30,000
+Now we can say that our table meets the requirements of the first normal form.
+
+230
+00:18:31,000 --> 00:18:34,000
+Now, it is time for the second normal form.
+
+231
+00:18:35,000 --> 00:18:40,000
+Revelation is in second normal form, if it fulfils is a following two requirements.
+
+232
+00:18:41,000 --> 00:18:46,000
+It is in first normal form and it doesn't have any non-prime attribute.
+
+233
+00:18:47,000 --> 00:18:51,000
+It is functioning dependent on any proper subset of any candidate.
+
+234
+00:18:51,000 --> 00:18:59,000
+Key of the relation and non-prime attribute of a relation is an attribute that is not part of any candidate
+
+235
+00:18:59,000 --> 00:19:00,000
+key of their relation.
+
+236
+00:19:01,000 --> 00:19:08,000
+In simple words, you have to store maintains a table that relates only to the current entity, but
+
+237
+00:19:08,000 --> 00:19:09,000
+not another one.
+
+238
+00:19:10,000 --> 00:19:16,000
+All attributes should depend on the whole primary key, especially if this is compound primary.
+
+239
+00:19:16,000 --> 00:19:23,000
+Key attributes should have complete functional dependency was the whole columns in compound key.
+
+240
+00:19:23,000 --> 00:19:26,000
+But not only on its part.
+
+241
+00:19:26,000 --> 00:19:32,000
+This might sound complicated at the beginning, but in real life it is much simpler than you think.
+
+242
+00:19:33,000 --> 00:19:35,000
+Let me show you this one example.
+
+243
+00:19:35,000 --> 00:19:38,000
+I believe it will be easier to understand.
+
+244
+00:19:38,000 --> 00:19:42,000
+Here's a table of items that we sell in our store.
+
+245
+00:19:42,000 --> 00:19:46,000
+We have category neat discount and product name.
+
+246
+00:19:46,000 --> 00:19:52,000
+There is compound primary key that consists from category and date from this table.
+
+247
+00:19:52,000 --> 00:19:58,000
+We can now discount that should be applied to goods from specific category at specific date.
+
+248
+00:19:59,000 --> 00:20:04,000
+I believe that based on my explanation, you already understood what is wrong here.
+
+249
+00:20:04,000 --> 00:20:08,000
+This gown depends only on the product category and date.
+
+250
+00:20:08,000 --> 00:20:14,000
+That said, there is no direct dependency between discount and specific product.
+
+251
+00:20:15,000 --> 00:20:18,000
+Product depends only on the quiet of the primary key.
+
+252
+00:20:19,000 --> 00:20:21,000
+I mean, only on the category.
+
+253
+00:20:21,000 --> 00:20:27,000
+There is a dependency between discount for products from specific categories at a particular date.
+
+254
+00:20:27,000 --> 00:20:33,000
+Does it make sense because in this case, we have data redundancy?
+
+255
+00:20:33,000 --> 00:20:36,000
+So what would be a solution here?
+
+256
+00:20:36,000 --> 00:20:42,000
+The solution here is to make sure that complete functional dependency exists between all attributes
+
+257
+00:20:43,000 --> 00:20:44,000
+and primary key.
+
+258
+00:20:44,000 --> 00:20:51,000
+In our case, product has functional dependency category, but not with category and date.
+
+259
+00:20:52,000 --> 00:20:56,000
+That's why we create two tables in the first table.
+
+260
+00:20:56,000 --> 00:21:00,000
+We are going to have information about discount for category in particular date.
+
+261
+00:21:00,000 --> 00:21:04,000
+And then the second table, we're going to store all products.
+
+262
+00:21:04,000 --> 00:21:08,000
+This will allow us to have cleaner DB architecture.
+
+263
+00:21:09,000 --> 00:21:15,000
+Let's learn certain amount form, and then the basic relation is set to meet certain normal form standards.
+
+264
+00:21:15,000 --> 00:21:22,000
+If all the I think it's function dependent on Sullivan's primary key without any transitive dependencies,
+
+265
+00:21:23,000 --> 00:21:29,000
+then Xenia of the third normal form is to not store data and tables that can be retrieved from other
+
+266
+00:21:29,000 --> 00:21:30,000
+table attributes.
+
+267
+00:21:31,000 --> 00:21:34,000
+Imagine that we have a table of two users at the university.
+
+268
+00:21:34,000 --> 00:21:36,000
+We have such columns.
+
+269
+00:21:36,000 --> 00:21:42,000
+I need less name, title, salary department and phone number.
+
+270
+00:21:42,000 --> 00:21:45,000
+Is this table in the third normal form?
+
+271
+00:21:45,000 --> 00:21:47,000
+I don't think so.
+
+272
+00:21:47,000 --> 00:21:49,000
+Let's try to visualize dependencies here.
+
+273
+00:21:50,000 --> 00:21:56,000
+Salary depends on the title only it doesn't depend on specific person.
+
+274
+00:21:57,000 --> 00:22:04,000
+Specific tutor has its own title and works in concrete department, and they don't have personal work
+
+275
+00:22:04,000 --> 00:22:10,000
+phone numbers you can contact with them using phone in the department.
+
+276
+00:22:10,000 --> 00:22:18,000
+That's why we can say that there are different transitive dependencies, for example, transitive dependency
+
+277
+00:22:18,000 --> 00:22:26,000
+between concrete tutor department where he or she works, and phone number there is transitive dependency
+
+278
+00:22:26,000 --> 00:22:28,000
+between phone number and tutor.
+
+279
+00:22:28,000 --> 00:22:29,000
+Is it clear?
+
+280
+00:22:30,000 --> 00:22:36,000
+To remove all transitive dependencies and make sure that all relations means a certain normal form.
+
+281
+00:22:36,000 --> 00:22:39,000
+Let's split this data between different tables.
+
+282
+00:22:39,000 --> 00:22:46,000
+We need to create three tables to achieve this cuter table was last name, title and deportment.
+
+283
+00:22:46,000 --> 00:22:53,000
+Title table was titled Name Unrelated Salary Department Table was its name and phone.
+
+284
+00:22:53,000 --> 00:22:56,000
+That's it for some of my students.
+
+285
+00:22:56,000 --> 00:22:58,000
+Nothing is changed as a first glance.
+
+286
+00:22:59,000 --> 00:23:05,000
+We just have more tables and the relationships between different tables rather than storing old data
+
+287
+00:23:05,000 --> 00:23:06,000
+in one table in one place.
+
+288
+00:23:07,000 --> 00:23:09,000
+And you need to understand me, correct?
+
+289
+00:23:09,000 --> 00:23:12,000
+Because you can store everything in one table.
+
+290
+00:23:12,000 --> 00:23:14,000
+This is even has its own name.
+
+291
+00:23:15,000 --> 00:23:16,000
+No sequel.
+
+292
+00:23:16,000 --> 00:23:23,000
+Just to let you know that this is also possible, but you would lose advantage is its relational database
+
+293
+00:23:23,000 --> 00:23:24,000
+is all for you.
+
+294
+00:23:24,000 --> 00:23:30,000
+If you opt for relational databases, you need to clearly understand what advantage you expect to get
+
+295
+00:23:30,000 --> 00:23:31,000
+from it.
+
+296
+00:23:31,000 --> 00:23:39,000
+That's why the rule of thumb is to follow normal forms called later realized that certain normal form
+
+297
+00:23:39,000 --> 00:23:46,000
+did not eliminate all undesirable data anomalies and developed a strong aversion to address this in
+
+298
+00:23:46,000 --> 00:23:51,000
+1974, known as voice called normal form.
+
+299
+00:23:51,000 --> 00:23:56,000
+To be honest, yeah, many other normal forms on top of these that we have just discussed.
+
+300
+00:23:57,000 --> 00:24:03,000
+But in my opinion, this three as the most important ones, I'm still going to make a quick overview
+
+301
+00:24:03,000 --> 00:24:05,000
+of other normal forms, at least on the high level.
+
+302
+00:24:06,000 --> 00:24:12,000
+In case you would be interested in more detailed explanation of all other normal forms, we don't just
+
+303
+00:24:12,000 --> 00:24:16,000
+have any question related to normal forms reviewed in this lesson.
+
+304
+00:24:16,000 --> 00:24:21,000
+Please ask me in the comments below this video, and I will be happy to answer you.
+
+305
+00:24:22,000 --> 00:24:27,000
+Elementary Queen Normal fall is a subtle enhancement on certain minimal form.
+
+306
+00:24:27,000 --> 00:24:32,000
+Thus, E K and AV tables are insert normal form by definition.
+
+307
+00:24:33,000 --> 00:24:38,000
+This happens when there is more than one unique compound key, and they overlap.
+
+308
+00:24:39,000 --> 00:24:43,000
+Such cases can, of course, redundant information in the overlapping columns.
+
+309
+00:24:44,000 --> 00:24:52,000
+A table is an elementary key normal form if and only if all its elementary functional dependencies begin
+
+310
+00:24:52,000 --> 00:24:56,000
+at whole keys or and elementary key attributes.
+
+311
+00:24:57,000 --> 00:25:04,000
+Voice called normal form is slightly stronger version of the third normal form if relational schema
+
+312
+00:25:04,000 --> 00:25:10,000
+is in the called normal form zone, all redundancy based on functional dependency has been removed.
+
+313
+00:25:11,000 --> 00:25:14,000
+Also, other types of redundancy may still exist.
+
+314
+00:25:15,000 --> 00:25:22,000
+Force normal form is concerned was a more general type of dependency known as mutually dependency.
+
+315
+00:25:23,000 --> 00:25:31,000
+A table is enforced normal form if and only if, for every one of its non-travel lots of other dependencies.
+
+316
+00:25:31,000 --> 00:25:39,000
+X y x is a super key that is X. This is a candidate key or a superset zero.
+
+317
+00:25:41,000 --> 00:25:47,000
+Essential double normal form for relations is a relational database where the constraints are given
+
+318
+00:25:47,000 --> 00:25:50,000
+by functional dependencies and joint dependencies.
+
+319
+00:25:51,000 --> 00:25:58,000
+It lies strictly between first and fourth and fifth normal for our relations schema is an essential
+
+320
+00:25:58,000 --> 00:26:07,000
+double normal form if and only if it is invoiced called normal form and some component of every explicitly
+
+321
+00:26:07,000 --> 00:26:12,000
+declared during the pendency of the schema is a superkick thief's normal form.
+
+322
+00:26:13,000 --> 00:26:15,000
+Also known as project joined.
+
+323
+00:26:15,000 --> 00:26:22,000
+Normal form is a level of database normalization designed to reduce redundancy in relational databases,
+
+324
+00:26:22,000 --> 00:26:29,000
+recording multivariate facts but isolate and semantically related to multiple relationships.
+
+325
+00:26:29,000 --> 00:26:37,000
+A table is set to be in the fifth normal form if and only if every non-trivial joint dependency in that
+
+326
+00:26:37,000 --> 00:26:40,000
+table is implied by the candidate keys.
+
+327
+00:26:41,000 --> 00:26:49,000
+The main key normal form is a normal form used in database normalization, which requires the database
+
+328
+00:26:49,000 --> 00:26:56,000
+contains no constraints, Aussies and domain constraints and key constraints and domain constraints
+
+329
+00:26:56,000 --> 00:26:59,000
+insofar as a permissible values for a given attribute.
+
+330
+00:27:00,000 --> 00:27:07,000
+While a key constraint specifies is, it attributes that uniquely identify a role in a given table.
+
+331
+00:27:08,000 --> 00:27:15,000
+The new key normal form is achieved when every constraint on the relation is a logical consequence of
+
+332
+00:27:15,000 --> 00:27:21,000
+the definition of keys and the means and enforcing key and the main, the restraints and conditions
+
+333
+00:27:22,000 --> 00:27:24,000
+causes all constraints to be met.
+
+334
+00:27:24,000 --> 00:27:28,000
+Thus, it avoids all non temporal anomalies.
+
+335
+00:27:29,000 --> 00:27:29,000
+Six.
+
+336
+00:27:29,000 --> 00:27:38,000
+Normal form is intended to decompose relation variables to irreducible components, though this may
+
+337
+00:27:38,000 --> 00:27:41,000
+be relatively unimportant for non temporal relation variables.
+
+338
+00:27:42,000 --> 00:27:48,000
+It can be important when dealing with temporal variables or other internal data.
+
+339
+00:27:48,000 --> 00:27:57,000
+A table is in six normal form if and only if it satisfies no non-trivial joint dependencies at all.
+
+340
+00:27:57,000 --> 00:28:05,000
+Where, as before and during dependencies is trivial if and only if at least one of the projections
+
+341
+00:28:05,000 --> 00:28:10,000
+involved is taken over a set of all attributes of the table concerned.
+
+342
+00:28:11,000 --> 00:28:18,000
+As you see from high level overview, it might be not so easy to understand the practical need and value
+
+343
+00:28:18,000 --> 00:28:22,000
+of each of these normal forms to know how to apply.
+
+344
+00:28:22,000 --> 00:28:26,000
+Those probably separate lesson is needed for each.
+
+345
+00:28:26,000 --> 00:28:32,000
+But considering the fact that they are not so popular in comparison with the first three normal forms,
+
+346
+00:28:32,000 --> 00:28:35,000
+probably I will not cover them in detail in this lesson.
+
+347
+00:28:36,000 --> 00:28:43,000
+I strongly recommend you to apply first three normal forms during database architecture and during creation
+
+348
+00:28:43,000 --> 00:28:44,000
+of each table.
+
+349
+00:28:44,000 --> 00:28:50,000
+I might add, means that knowing of all other normal forms by heart is not so critical.
+
+350
+00:28:50,000 --> 00:28:56,000
+On the slide, you can see comparative analysis and the last, but not the least, things that I wanted
+
+351
+00:28:56,000 --> 00:28:59,000
+to discuss with you today is the normalization.
+
+352
+00:29:00,000 --> 00:29:07,000
+No normalization is a strategy used on the previously normalized database to increase performance in
+
+353
+00:29:07,000 --> 00:29:07,000
+computing.
+
+354
+00:29:07,000 --> 00:29:14,000
+The normalization is a process of trying to improve the performance of a database and the expense of
+
+355
+00:29:14,000 --> 00:29:20,000
+losing some light performance by adding redundant corpus of data all by group and later.
+
+356
+00:29:21,000 --> 00:29:27,000
+The normalization difference from a normalized form means that the normalization benefits can only be
+
+357
+00:29:27,000 --> 00:29:32,000
+fully realized on the data model that is otherwise normalized.
+
+358
+00:29:33,000 --> 00:29:35,000
+So how we can improve performance.
+
+359
+00:29:36,000 --> 00:29:43,000
+Imagine that we have multiple tables, we have table with soccer clubs, we have a table with soccer
+
+360
+00:29:43,000 --> 00:29:50,000
+leagues and we have table was match data that should contain information about me, home team and guests.
+
+361
+00:29:52,000 --> 00:29:55,000
+We also saw a lot of other information about teams and matches.
+
+362
+00:29:56,000 --> 00:30:04,000
+Now imagine that to extract much data for the home, the week moments, we need to query suite tables
+
+363
+00:30:04,000 --> 00:30:06,000
+and database for each row.
+
+364
+00:30:06,000 --> 00:30:11,000
+We may have spouses of matches and not only soccer.
+
+365
+00:30:11,000 --> 00:30:18,000
+I simplified the original example a bit, but imagine that you have multiple sports and you have teams
+
+366
+00:30:18,000 --> 00:30:21,000
+and different sports and much more leagues.
+
+367
+00:30:21,000 --> 00:30:25,000
+This is literally crazy amount of data each day.
+
+368
+00:30:25,000 --> 00:30:33,000
+Making Junqueras findings and mappings in different tables may take some time, while it might be not
+
+369
+00:30:33,000 --> 00:30:36,000
+so dramatic while querying a few records.
+
+370
+00:30:36,000 --> 00:30:44,000
+It is different when you query a lot of records, and that is a day we are receiving benefits by certain
+
+371
+00:30:44,000 --> 00:30:47,000
+entities in different tables without any duplication.
+
+372
+00:30:48,000 --> 00:30:55,000
+But when you query Susan's rose and do join requests with different tables, this might take some time
+
+373
+00:30:56,000 --> 00:31:00,000
+and to save time by not comparing other tables to get data you need.
+
+374
+00:31:00,000 --> 00:31:08,000
+We at data redundancy on purpose and understand know how better performance of reading operations is
+
+375
+00:31:08,000 --> 00:31:08,000
+achieved.
+
+376
+00:31:09,000 --> 00:31:17,000
+Imagine you need to read all matches, data in normalized database and you query in different tables
+
+377
+00:31:17,000 --> 00:31:25,000
+and you normalize database, you request all data from one place, then distanza mean a year of generalization.
+
+378
+00:31:26,000 --> 00:31:30,000
+But remember, this is something what should be done super carefully.
+
+379
+00:31:30,000 --> 00:31:37,000
+You need to be sure what benefits you will get from generalization, and it is recommended to be specific
+
+380
+00:31:37,000 --> 00:31:38,000
+in order.
+
+381
+00:31:38,000 --> 00:31:44,000
+You could understand how many seconds you would win in performance after the normalization.
+
+382
+00:31:44,000 --> 00:31:50,000
+I did this several times in my own projects, and I can say that this is a technique that's really worth
+
+383
+00:31:50,000 --> 00:31:53,000
+of your attention if you are going to use a smart.
+
+384
+00:31:54,000 --> 00:31:57,000
+That's all what I wanted to share with you in this lesson.
+
+385
+00:31:57,000 --> 00:32:01,000
+Let's recap what we have learned to date in this lesson.
+
+386
+00:32:01,000 --> 00:32:08,000
+You've learned what data anomalies are we have learned in session update and deletion anomalies.
+
+387
+00:32:09,000 --> 00:32:12,000
+Also, we reviewed the main concept in dependencies theory.
+
+388
+00:32:13,000 --> 00:32:17,000
+Now you know what a complete, unknown, complete functional dependency is.
+
+389
+00:32:18,000 --> 00:32:26,000
+After that, we learned what normalization is on examples of used normal forms and incentives was lesson
+
+390
+00:32:26,000 --> 00:32:27,000
+I explained.
+
+391
+00:32:27,000 --> 00:32:30,000
+What generalization is that?
+
+392
+00:32:30,000 --> 00:32:31,000
+So for this lesson?
+
+393
+00:32:31,000 --> 00:32:32,000
+Thanks a lot for your attention.
+
+394
+00:32:33,000 --> 00:32:35,000
+Have a great day and see you in the next lesson.
+

48 - SQL/001 MySQL-Documentation-about-statements.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://dev.mysql.com/doc/refman/8.0/en/create-view.html

48 - SQL/001 Query-Examples-that-were-shown-in-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/ddl

48 - SQL/001 SQL General Overview & DDL_en.srt

@@ -0,0 +1,976 @@
+1
+00:00:05,000 --> 00:00:06,000
+Hello, Kim.
+
+2
+00:00:06,000 --> 00:00:12,000
+Today, we're going to have a very important lesson in the lesson we are going to learn the basics of
+
+3
+00:00:12,000 --> 00:00:13,000
+structured query language.
+
+4
+00:00:14,000 --> 00:00:18,000
+I'm going to explain you what it is and why it is important to know it.
+
+5
+00:00:19,000 --> 00:00:22,000
+The work was databases will start from the very basics.
+
+6
+00:00:23,000 --> 00:00:25,000
+We'll learn what skill is in general.
+
+7
+00:00:26,000 --> 00:00:30,000
+And after that, we'll focus on data, definition, language and skill.
+
+8
+00:00:31,000 --> 00:00:35,000
+Don't worry, we'll not have only one lesson about sequel.
+
+9
+00:00:35,000 --> 00:00:38,000
+Still, there will be other lessons to learn.
+
+10
+00:00:38,000 --> 00:00:44,000
+But today we're going to build a basement for our further learning in the lesson we're going to learn
+
+11
+00:00:44,000 --> 00:00:45,000
+what sequel is.
+
+12
+00:00:45,000 --> 00:00:47,000
+I will explain what sequels have.
+
+13
+00:00:47,000 --> 00:00:48,000
+Languages are.
+
+14
+00:00:49,000 --> 00:00:52,000
+This will give you insights on what we are going to learn in this course.
+
+15
+00:00:53,000 --> 00:00:58,000
+After holding an overview of sequel language, we'll jump to learning of the first sequel.
+
+16
+00:00:58,000 --> 00:01:04,000
+Sub Language will learn data definition language in this video will review different statements with
+
+17
+00:01:04,000 --> 00:01:08,000
+great alter, rename, truncate and drop statements.
+
+18
+00:01:09,000 --> 00:01:16,000
+Also on the real examples you are going to see how we can create these statements and execute them against
+
+19
+00:01:16,000 --> 00:01:17,000
+our database.
+
+20
+00:01:17,000 --> 00:01:18,000
+Enough docs.
+
+21
+00:01:19,000 --> 00:01:22,000
+US start our lesson and to start our lesson.
+
+22
+00:01:22,000 --> 00:01:26,000
+Let's understand what sequel is and what we are going to learn in this course.
+
+23
+00:01:27,000 --> 00:01:29,000
+Sequel stands for structured query language.
+
+24
+00:01:30,000 --> 00:01:36,000
+It is the main specific language used to manage data held in the relational database management system.
+
+25
+00:01:36,000 --> 00:01:42,000
+Sequel was one of the first commercial languages to use anger cause relational model.
+
+26
+00:01:43,000 --> 00:01:50,000
+The model was described in his influential 1970 paper, a relational model of data for large shared
+
+27
+00:01:51,000 --> 00:01:51,000
+data banks.
+
+28
+00:01:52,000 --> 00:02:00,000
+Despite not entirely adhering to the relational model as described by code, it became most widely used.
+
+29
+00:02:00,000 --> 00:02:03,000
+Database language sequel became a standard.
+
+30
+00:02:03,000 --> 00:02:09,000
+Often, the American National Standards Institute in nineteen eighty six and all was the International
+
+31
+00:02:09,000 --> 00:02:13,000
+Organization for Standardization in 1987.
+
+32
+00:02:13,000 --> 00:02:19,000
+And because standardization of sequel wasn't done since its creation defines relational database management
+
+33
+00:02:19,000 --> 00:02:22,000
+systems invented their own differences.
+
+34
+00:02:22,000 --> 00:02:29,000
+Despite the existence of standards, most sequel code requires at least some minor changes before being
+
+35
+00:02:29,000 --> 00:02:31,000
+ported to different database systems.
+
+36
+00:02:32,000 --> 00:02:39,000
+So SQL itself is set of operators that allow us to interact with database management system, query
+
+37
+00:02:39,000 --> 00:02:42,000
+data in it and perform other operations.
+
+38
+00:02:43,000 --> 00:02:49,000
+These different statements and operators informally can be grouped and classified as different sublineages.
+
+39
+00:02:50,000 --> 00:02:58,000
+Ziya Data Definition Language It is a syntax for creating and modifying database objects such as tables,
+
+40
+00:02:58,000 --> 00:03:06,000
+indexes, etc. DDL statements are similar to a computer programming language for defining data structures,
+
+41
+00:03:06,000 --> 00:03:09,000
+especially database schemas.
+
+42
+00:03:09,000 --> 00:03:14,000
+Common examples of these statements include create, alter and draw.
+
+43
+00:03:15,000 --> 00:03:22,000
+Data manipulation language, is this a set of statements that they used for adding deleting dating data
+
+44
+00:03:22,000 --> 00:03:23,000
+in a database?
+
+45
+00:03:23,000 --> 00:03:27,000
+Common examples of these misstatements include select insert.
+
+46
+00:03:27,000 --> 00:03:29,000
+Update Delete.
+
+47
+00:03:30,000 --> 00:03:37,000
+Data control language, it is a syntax that is used to control access to data stored in a database.
+
+48
+00:03:37,000 --> 00:03:42,000
+Examples of this sale include grant and revoke statements.
+
+49
+00:03:43,000 --> 00:03:47,000
+And last but not least siblings, which is transaction control language.
+
+50
+00:03:47,000 --> 00:03:53,000
+This language group statements to manage transactions in databases and one examples of this.
+
+51
+00:03:53,000 --> 00:03:57,000
+It is worth to mention commit, rollback and safe points.
+
+52
+00:03:58,000 --> 00:04:05,000
+Based on this, we can make a conclusion that the scope of sequel includes data query, data manipulation,
+
+53
+00:04:05,000 --> 00:04:13,000
+data definition, data access control, transaction management and managing database objects in our
+
+54
+00:04:13,000 --> 00:04:14,000
+course on real examples.
+
+55
+00:04:14,000 --> 00:04:18,000
+We are going to learn how to work with different groups of statements.
+
+56
+00:04:19,000 --> 00:04:19,000
+OK.
+
+57
+00:04:20,000 --> 00:04:25,000
+I believe that now you understand what a sequel is and what we are going to learn.
+
+58
+00:04:25,000 --> 00:04:32,000
+And as we announced an agenda of this meeting, let's start learning the deal now and we will start
+
+59
+00:04:32,000 --> 00:04:33,000
+from the first statement.
+
+60
+00:04:34,000 --> 00:04:35,000
+It is a great statement.
+
+61
+00:04:36,000 --> 00:04:42,000
+The general structure of statement is the following you write create first.
+
+62
+00:04:42,000 --> 00:04:49,000
+After that, you specify what you want to create, whether it is a database schema to move you index.
+
+63
+00:04:50,000 --> 00:04:56,000
+After that, you put name of the database object that you want to create and optionally you can put
+
+64
+00:04:56,000 --> 00:04:57,000
+different options.
+
+65
+00:04:58,000 --> 00:04:59,000
+Let's review a few queries with you.
+
+66
+00:05:00,000 --> 00:05:03,000
+Degrade database We need to use the following construct.
+
+67
+00:05:04,000 --> 00:05:06,000
+We start from create keywords.
+
+68
+00:05:06,000 --> 00:05:10,000
+After that, we indicate that we want to create a database.
+
+69
+00:05:11,000 --> 00:05:19,000
+And by the way, in my school you can use both options is a create schema or create database.
+
+70
+00:05:19,000 --> 00:05:20,000
+They are similar.
+
+71
+00:05:21,000 --> 00:05:24,000
+After that, we need to specify name of the database.
+
+72
+00:05:24,000 --> 00:05:29,000
+Usually in sequel, we use single quotes for all string values.
+
+73
+00:05:30,000 --> 00:05:33,000
+That's why I put the name of our DB in quotes.
+
+74
+00:05:34,000 --> 00:05:37,000
+Basically, this is enough to create a database.
+
+75
+00:05:38,000 --> 00:05:41,000
+But additionally, we can add more sinks in the statement.
+
+76
+00:05:42,000 --> 00:05:48,000
+We can add a condition to make sure that we wouldn't even try to create a table if it exists already
+
+77
+00:05:49,000 --> 00:05:49,000
+for this.
+
+78
+00:05:49,000 --> 00:05:57,000
+Optionally, we can add, if not exist and the different create options that can be specified separately.
+
+79
+00:05:58,000 --> 00:06:03,000
+For example, you know that sometimes we also want to specify charset and collation.
+
+80
+00:06:03,000 --> 00:06:09,000
+You can write default character set, followed by Charsadda, that you want to use.
+
+81
+00:06:09,000 --> 00:06:15,000
+And after that, you can write code and specify collation that will be used for this charset.
+
+82
+00:06:16,000 --> 00:06:20,000
+Now this is complete query to be executed against database.
+
+83
+00:06:21,000 --> 00:06:26,000
+Let me start sharing my screen to execute this query together with you.
+
+84
+00:06:26,000 --> 00:06:31,000
+I'm going to show you how you can execute cycle queries from my SQL workbench.
+
+85
+00:06:32,000 --> 00:06:37,000
+If you don't have my SQL server installed and also you don't have my SQL workbench in your computer,
+
+86
+00:06:38,000 --> 00:06:44,000
+please refer to the previous classes where we together installed all required applications for my school
+
+87
+00:06:44,000 --> 00:06:46,000
+relational database management system.
+
+88
+00:06:47,000 --> 00:06:52,000
+You can execute any SQL query you wish directly from sequel editor.
+
+89
+00:06:53,000 --> 00:07:00,000
+Just click on this icon that is called Create New SQL tab for executing queries and Knewthat will be
+
+90
+00:07:00,000 --> 00:07:01,000
+opened.
+
+91
+00:07:01,000 --> 00:07:07,000
+Now you can type any query you wish can save time during this video lesson.
+
+92
+00:07:07,000 --> 00:07:12,000
+I already pasted here's a query removed to create a database.
+
+93
+00:07:12,000 --> 00:07:17,000
+Press a pause for a few seconds if you need to times square it in a sequel editor.
+
+94
+00:07:18,000 --> 00:07:24,000
+One more important thing the mansion here is that sequel is not case sensitive.
+
+95
+00:07:24,000 --> 00:07:31,000
+That means that no matter how you would spell create, it would still mean the same.
+
+96
+00:07:31,000 --> 00:07:35,000
+You can write it with capital letters all lowercase.
+
+97
+00:07:35,000 --> 00:07:38,000
+Technically speaking, and doesn't matter at all.
+
+98
+00:07:38,000 --> 00:07:44,000
+But still, there is a common practice to write all sequel key words with capital letters.
+
+99
+00:07:45,000 --> 00:07:49,000
+If you are ready, let's execute the query to execute all commands.
+
+100
+00:07:49,000 --> 00:07:57,000
+Since this SQL file, you have to click this lightning icon if you want to execute on the selected commands.
+
+101
+00:07:57,000 --> 00:08:03,000
+We have to select first SQL instruction, and after that, click on Lightning Icon.
+
+102
+00:08:04,000 --> 00:08:10,000
+And if you want to execute only one statement on the keyboard's cursor, you have to click this icon.
+
+103
+00:08:11,000 --> 00:08:16,000
+I execute query after it has been successfully executed.
+
+104
+00:08:16,000 --> 00:08:21,000
+I click Refresh Icon and I see that new database is created.
+
+105
+00:08:21,000 --> 00:08:28,000
+Let me select this database to make sure that all other queries will be executed against this database.
+
+106
+00:08:29,000 --> 00:08:36,000
+I am going to save each query that will review today with you in a separate file in attachments to the
+
+107
+00:08:36,000 --> 00:08:39,000
+lesson, you will be able to find all these queries.
+
+108
+00:08:40,000 --> 00:08:43,000
+Now, let's learn how we can create table.
+
+109
+00:08:44,000 --> 00:08:50,000
+I believe you already understood the general structure of great query, but still on the slide you can
+
+110
+00:08:50,000 --> 00:08:53,000
+see specifics of create table statement.
+
+111
+00:08:53,000 --> 00:08:57,000
+This query is much more complicated than create database query.
+
+112
+00:08:57,000 --> 00:09:04,000
+We can come up with some different combinations and variations that it will take more than one slides
+
+113
+00:09:04,000 --> 00:09:05,000
+to describe all of them.
+
+114
+00:09:06,000 --> 00:09:09,000
+That's why I would try to share with you.
+
+115
+00:09:09,000 --> 00:09:15,000
+The most general and high level structure of this statement mentions the most important things, in
+
+116
+00:09:15,000 --> 00:09:16,000
+my opinion.
+
+117
+00:09:16,000 --> 00:09:22,000
+In case you would like to know more details, you can always refer to the official documentation.
+
+118
+00:09:23,000 --> 00:09:31,000
+Basically, when you try to create stable followed by table name and after that parentheses, we have
+
+119
+00:09:31,000 --> 00:09:37,000
+to list all columns with their data types specifying size for each field.
+
+120
+00:09:37,000 --> 00:09:46,000
+If needed, we can specify primary key column name and if we need, we can create index by specifying
+
+121
+00:09:46,000 --> 00:09:54,000
+its style column name sorting that might be easier ascendent understanding and its visibility.
+
+122
+00:09:55,000 --> 00:10:01,000
+Just to remind you that it might be visible or not visible in case you're not familiar with indexes
+
+123
+00:10:01,000 --> 00:10:01,000
+and databases.
+
+124
+00:10:02,000 --> 00:10:08,000
+Please make sure you watched the previous lesson in this course about indexes in databases.
+
+125
+00:10:08,000 --> 00:10:16,000
+We reviewed all properties of indexes, any details on the example you can see and after you listed
+
+126
+00:10:16,000 --> 00:10:20,000
+all columns and added necessary properties to columns.
+
+127
+00:10:20,000 --> 00:10:24,000
+We can specify engine type that we want to use for this table.
+
+128
+00:10:25,000 --> 00:10:32,000
+I believe you remember that we can specify charset and collation on different levels, the specified
+
+129
+00:10:32,000 --> 00:10:35,000
+SHAZAD and collation on the table level.
+
+130
+00:10:35,000 --> 00:10:38,000
+You can put these statements at the end of the query.
+
+131
+00:10:38,000 --> 00:10:39,000
+That's it.
+
+132
+00:10:40,000 --> 00:10:43,000
+Let's execute real query against database.
+
+133
+00:10:44,000 --> 00:10:50,000
+Here, an example you can see SQL create statement that will create separate table for us was named
+
+134
+00:10:50,000 --> 00:10:52,000
+best table in this database.
+
+135
+00:10:53,000 --> 00:10:55,000
+Pay attention to a separate database.
+
+136
+00:10:55,000 --> 00:11:02,000
+Name and table name was Dot in case you selected this database in my school workbench.
+
+137
+00:11:02,000 --> 00:11:10,000
+There is no need to specify the full table name to make sure it will be created in the current database.
+
+138
+00:11:11,000 --> 00:11:16,000
+In this case, this declaration is redundant and you can remove it.
+
+139
+00:11:16,000 --> 00:11:18,000
+Result will be the same.
+
+140
+00:11:19,000 --> 00:11:22,000
+Here is a list of attributes that I want to have in my table.
+
+141
+00:11:23,000 --> 00:11:28,000
+Next to an attribute, I specify all properties related to this column.
+
+142
+00:11:29,000 --> 00:11:36,000
+It is a type and not now and all the incremented first name attribute is of type word.
+
+143
+00:11:36,000 --> 00:11:42,000
+Char was maximum lengths of forty five with no default value and so on.
+
+144
+00:11:43,000 --> 00:11:51,000
+Primary key is ID column I create a unique index was name email, unique for email column with ascending
+
+145
+00:11:51,000 --> 00:11:57,000
+order and also I specify engine charset and collation.
+
+146
+00:11:57,000 --> 00:11:58,000
+Is that clear?
+
+147
+00:11:59,000 --> 00:12:05,000
+And even in case you have any questions, you can always ask your questions in comments to the reader,
+
+148
+00:12:05,000 --> 00:12:07,000
+and I will be happy to answer.
+
+149
+00:12:08,000 --> 00:12:13,000
+Let's execute this query and we seize that query has been successfully executed.
+
+150
+00:12:13,000 --> 00:12:17,000
+After we refresh, we seize a test table is created.
+
+151
+00:12:21,000 --> 00:12:25,000
+You already saw how to create index during the creation of the table.
+
+152
+00:12:26,000 --> 00:12:31,000
+But let's imagine that we create a table and we simply forgot to create an index.
+
+153
+00:12:32,000 --> 00:12:34,000
+We still can create index afterwards.
+
+154
+00:12:35,000 --> 00:12:38,000
+Let's learn how to do this on this slide.
+
+155
+00:12:38,000 --> 00:12:42,000
+You can see structure of create in the statement you're in the creation.
+
+156
+00:12:42,000 --> 00:12:46,000
+We need to specify which type of index we would like to create.
+
+157
+00:12:46,000 --> 00:12:51,000
+The difference between these types was covered in the lesson about indexes.
+
+158
+00:12:52,000 --> 00:13:00,000
+You specify index name and on which table and column you would like to create this and this on the slide.
+
+159
+00:13:00,000 --> 00:13:07,000
+You can also notice that there might be different index options, index types, algorithm options and
+
+160
+00:13:07,000 --> 00:13:08,000
+lock options.
+
+161
+00:13:09,000 --> 00:13:12,000
+Let's grade index for our new table.
+
+162
+00:13:12,000 --> 00:13:17,000
+Just for the sake of example, let's create an index for the first name column.
+
+163
+00:13:18,000 --> 00:13:19,000
+I'm here on the screen.
+
+164
+00:13:19,000 --> 00:13:23,000
+You can see a simplified version of Create Index.
+
+165
+00:13:23,000 --> 00:13:30,000
+I specify name of my index table column in this table and index option.
+
+166
+00:13:30,000 --> 00:13:32,000
+Let me ask the this query.
+
+167
+00:13:33,000 --> 00:13:41,000
+We see the query has been executed successfully, but it is obvious that no rows were affected to make
+
+168
+00:13:41,000 --> 00:13:44,000
+sure that we really created the index when needed.
+
+169
+00:13:44,000 --> 00:13:52,000
+I open all the table and on index type I can see as an index was my name that I have just great.
+
+170
+00:13:53,000 --> 00:13:55,000
+That's how easily I can create indexes.
+
+171
+00:13:56,000 --> 00:14:02,000
+Also, index might be added as part of output table instruction, but we are going to use this later
+
+172
+00:14:02,000 --> 00:14:07,000
+in our lesson when we'll start learning of all the statement and details.
+
+173
+00:14:08,000 --> 00:14:15,000
+One of my main goal as a tutor is not just to teach you each possible combination of swearing, but
+
+174
+00:14:15,000 --> 00:14:22,000
+also I have to teach you how to understand the documentation in order you could easily proceed yourself
+
+175
+00:14:22,000 --> 00:14:23,000
+education.
+
+176
+00:14:23,000 --> 00:14:26,000
+The Gazette reviewed few queries already.
+
+177
+00:14:27,000 --> 00:14:33,000
+And for example, if you need to create view via a sequel, you don't need to open this lesson.
+
+178
+00:14:33,000 --> 00:14:39,000
+You can always open the official documentation of specific relational database management system and
+
+179
+00:14:39,000 --> 00:14:40,000
+check the details.
+
+180
+00:14:41,000 --> 00:14:46,000
+For example, now on the screen, you can see documentation page of my school.
+
+181
+00:14:47,000 --> 00:14:53,000
+From this page, you can find general construction of create, view statement and all possible options.
+
+182
+00:14:54,000 --> 00:15:00,000
+We have just reviewed similar ones, and I believe you'll really understand how to read this syntax
+
+183
+00:15:00,000 --> 00:15:01,000
+by analogy.
+
+184
+00:15:02,000 --> 00:15:08,000
+Press a pause for a minute, if needed, or just feel free to explore attachments to the lesson and
+
+185
+00:15:08,000 --> 00:15:12,000
+find this link to the official documentation that I've shared with you.
+
+186
+00:15:13,000 --> 00:15:18,000
+Additionally, if you scroll down a bit, you can also find examples of SQL queries.
+
+187
+00:15:19,000 --> 00:15:24,000
+You can create your own queries from database and your application by analogy.
+
+188
+00:15:25,000 --> 00:15:29,000
+And at the meantime, let's proceed with another examples.
+
+189
+00:15:30,000 --> 00:15:37,000
+Let's learn now such important statements as all the statements we use, all the statements when we
+
+190
+00:15:37,000 --> 00:15:44,000
+need to update the database object, no matter whether we need to update the database or table, we
+
+191
+00:15:44,000 --> 00:15:50,000
+are going to start query with all the keywords as you already know how to use the commendation.
+
+192
+00:15:50,000 --> 00:15:55,000
+I don't see a lot of reasons to go over each alter statement.
+
+193
+00:15:55,000 --> 00:15:57,000
+I mean, I will not damage you now.
+
+194
+00:15:57,000 --> 00:16:04,000
+All possible variations of all of the statements that includes and in columns and column properties
+
+195
+00:16:04,000 --> 00:16:08,000
+change enough charset and collation and lots more.
+
+196
+00:16:08,000 --> 00:16:12,000
+For the sake of the Namma, I will demo only one case was also in table.
+
+197
+00:16:12,000 --> 00:16:18,000
+In order you could understand how it works, let's adjust this table.
+
+198
+00:16:18,000 --> 00:16:26,000
+We are going to add new column after the first name and adjust first name index to change ordering in
+
+199
+00:16:26,000 --> 00:16:28,000
+there from ascending the descending.
+
+200
+00:16:29,000 --> 00:16:37,000
+I write alter table and after that I specifies a full table name, and after that I put instructions
+
+201
+00:16:37,000 --> 00:16:47,000
+related to my table of the I want to add column was name plus name was version, data type and default.
+
+202
+00:16:47,000 --> 00:16:56,000
+No value after first name column to accommodate index, I need to drop existing index first and after
+
+203
+00:16:56,000 --> 00:16:58,000
+that to add new index was descending.
+
+204
+00:16:58,000 --> 00:17:02,000
+Order Drop Command Remove Index.
+
+205
+00:17:03,000 --> 00:17:07,000
+Let me execute this query query is successfully executed.
+
+206
+00:17:08,000 --> 00:17:11,000
+Let's open table now and here is our new column.
+
+207
+00:17:12,000 --> 00:17:14,000
+We can also check our index.
+
+208
+00:17:15,000 --> 00:17:19,000
+We can see that we have to send an order in our index.
+
+209
+00:17:19,000 --> 00:17:23,000
+Basically, that's all what I wanted to share with you regarding all the query.
+
+210
+00:17:24,000 --> 00:17:29,000
+You can rename table using separate statement from data definition language.
+
+211
+00:17:29,000 --> 00:17:30,000
+It is called Renee.
+
+212
+00:17:31,000 --> 00:17:35,000
+We can easily rename our table to test DB.
+
+213
+00:17:36,000 --> 00:17:40,000
+And after refresh, we seize a table name has been changed.
+
+214
+00:17:41,000 --> 00:17:47,000
+One more interesting statement truncate we can create statements that will empty all table.
+
+215
+00:17:48,000 --> 00:17:54,000
+You to add some fake data in it first, for example, let me add just one row in this table.
+
+216
+00:17:55,000 --> 00:17:56,000
+Give me a few seconds.
+
+217
+00:18:07,000 --> 00:18:15,000
+As you see, now, we have some data in the table, and when I try to extract all the rows from table
+
+218
+00:18:15,000 --> 00:18:19,000
+one more time, I see that my role is in place.
+
+219
+00:18:20,000 --> 00:18:27,000
+If you're interested how to perform such basic operations as data insertion inside workbench, please
+
+220
+00:18:27,000 --> 00:18:30,000
+refer to lesson about my skill workbench.
+
+221
+00:18:31,000 --> 00:18:33,000
+Now we can execute the following statement.
+
+222
+00:18:34,000 --> 00:18:36,000
+TRUNCATE test to.
+
+223
+00:18:37,000 --> 00:18:39,000
+It should remove all rows in table.
+
+224
+00:18:40,000 --> 00:18:43,000
+And you can see that all rows have been removed.
+
+225
+00:18:44,000 --> 00:18:45,000
+Let's move on.
+
+226
+00:18:46,000 --> 00:18:53,000
+And the last, but not the listing for today that I'd like to show you is drop statements, we use drop
+
+227
+00:18:53,000 --> 00:18:56,000
+statement when we need to remove database object.
+
+228
+00:18:56,000 --> 00:19:02,000
+For example, if you want to remove a table or database, you have to use drop statement.
+
+229
+00:19:02,000 --> 00:19:05,000
+Let's review example of the nation of our database.
+
+230
+00:19:06,000 --> 00:19:13,000
+The database we have to execute the following query drop database and database name.
+
+231
+00:19:13,000 --> 00:19:17,000
+Everything is simple according to documentation you can add.
+
+232
+00:19:17,000 --> 00:19:22,000
+If exists, check a database only if it is present.
+
+233
+00:19:23,000 --> 00:19:24,000
+That's all for this lesson.
+
+234
+00:19:25,000 --> 00:19:27,000
+Let's recap what we have learned today.
+
+235
+00:19:28,000 --> 00:19:31,000
+We have learned a lot of different sinks in this lesson.
+
+236
+00:19:31,000 --> 00:19:33,000
+Some of them are now.
+
+237
+00:19:33,000 --> 00:19:36,000
+You know what sequel is after this lesson?
+
+238
+00:19:36,000 --> 00:19:38,000
+You know, sequels, some languages.
+
+239
+00:19:38,000 --> 00:19:47,000
+Zaire did the al DML DCL and to see out on real examples, we learned create statements.
+
+240
+00:19:48,000 --> 00:19:55,000
+Also, I explained all to rename, truncate and drop statements after this lesson, you know how to
+
+241
+00:19:55,000 --> 00:19:57,000
+build queries with mansion statements.
+
+242
+00:19:58,000 --> 00:20:00,000
+That's all for this lesson.
+
+243
+00:20:00,000 --> 00:20:02,000
+Thanks you all for your attention.
+
+244
+00:20:02,000 --> 00:20:05,000
+Have a great day and see you in the next lesson.
+

48 - SQL/002 INSERT-statement-documentation.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://dev.mysql.com/doc/refman/8.0/en/insert.html

48 - SQL/002 Query-Examples-that-were-shown-in-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/dml

48 - SQL/002 SQL DML - CRUD Operations (SELECT, INSERT, UPDATE, DELETE)_en.srt

@@ -0,0 +1,1380 @@
+1
+00:00:05,000 --> 00:00:06,000
+Hello, Tim.
+
+2
+00:00:06,000 --> 00:00:12,000
+Today we're going to learn data manipulation language will learn main statements from Male Group of
+
+3
+00:00:12,000 --> 00:00:13,000
+Sequel.
+
+4
+00:00:13,000 --> 00:00:19,000
+And will review real examples to help you understand how you can apply this knowledge on practice.
+
+5
+00:00:20,000 --> 00:00:27,000
+We'll start our lesson from understanding of select statements will spend a significant amount of power,
+
+6
+00:00:27,000 --> 00:00:34,000
+our lesson learned select statement considering that this is probably the most popular statement that
+
+7
+00:00:34,000 --> 00:00:42,000
+you are going to use it as different variations and options that I believe you should know that includes
+
+8
+00:00:42,000 --> 00:00:44,000
+order by were close.
+
+9
+00:00:44,000 --> 00:00:48,000
+Distinct search by pardon, et cetera.
+
+10
+00:00:48,000 --> 00:00:54,000
+I'm going to explain you different operators and sequels that you can use in your queries.
+
+11
+00:00:55,000 --> 00:00:59,000
+We'll review aggregate functions that are often used with select statements.
+
+12
+00:01:00,000 --> 00:01:06,000
+You're going to learn how to group result of select statement and apply condition on it.
+
+13
+00:01:06,000 --> 00:01:12,000
+And also, we're going to learn and review aussi important statements from your e-mail.
+
+14
+00:01:12,000 --> 00:01:17,000
+You'll see examples was insert, update and delete statements.
+
+15
+00:01:17,000 --> 00:01:19,000
+Let's start our lesson.
+
+16
+00:01:20,000 --> 00:01:28,000
+During your career as an engineer, you're going to hear very often such acronyms as crap it stands
+
+17
+00:01:28,000 --> 00:01:37,000
+for create, read, update, delete in computer programming crowd operations as a full basic operations
+
+18
+00:01:37,000 --> 00:01:38,000
+of persistent storage.
+
+19
+00:01:39,000 --> 00:01:48,000
+Craft is also sometimes used to describe user interface conventions that facilitate viewing, searching
+
+20
+00:01:48,000 --> 00:01:54,000
+and changing information using computer based forms and reports data manipulation.
+
+21
+00:01:54,000 --> 00:02:02,000
+Language describes syntax that will allow you to perform crud operations on the database layer, basically
+
+22
+00:02:03,000 --> 00:02:10,000
+to create, or, in other words, to insert rows in tables to read data from database or, in other
+
+23
+00:02:10,000 --> 00:02:18,000
+words, to select roles that match conditions to update throws and to delete rows that you don't need
+
+24
+00:02:18,000 --> 00:02:19,000
+anymore.
+
+25
+00:02:19,000 --> 00:02:24,000
+And the first statement that I'd like to review with you today is select statement.
+
+26
+00:02:25,000 --> 00:02:29,000
+This is a really important statement that I believe you are going to use very often.
+
+27
+00:02:29,000 --> 00:02:34,000
+That's why I would like to review different variations of the statement on the slide.
+
+28
+00:02:34,000 --> 00:02:38,000
+You can see how select statement is described in my sequel.
+
+29
+00:02:38,000 --> 00:02:39,000
+Official documentation.
+
+30
+00:02:40,000 --> 00:02:44,000
+As you can see, it contains really a lot of different variations.
+
+31
+00:02:45,000 --> 00:02:47,000
+Some of them, we are going to learn in this lesson.
+
+32
+00:02:48,000 --> 00:02:50,000
+Some of them will keep learning and other lessons.
+
+33
+00:02:51,000 --> 00:02:54,000
+Let me show you a simplified version of Select Statement.
+
+34
+00:02:55,000 --> 00:02:59,000
+On this slide, you see a simplified version of select statements.
+
+35
+00:02:59,000 --> 00:03:01,000
+Let's learn it for now.
+
+36
+00:03:01,000 --> 00:03:04,000
+And we are going to learn even more in practice.
+
+37
+00:03:05,000 --> 00:03:10,000
+You can write select, followed by asterisk from and specify table name.
+
+38
+00:03:11,000 --> 00:03:14,000
+Asterisk stands for all attributes.
+
+39
+00:03:14,000 --> 00:03:20,000
+This is like mask that is used to extract all attributes of selected tuple.
+
+40
+00:03:21,000 --> 00:03:25,000
+Next things you can see on this slide is example of search and query.
+
+41
+00:03:26,000 --> 00:03:32,000
+It is worth to say that searching on the database side is plus, rather than extracting onslaught of
+
+42
+00:03:32,000 --> 00:03:35,000
+data and sources in memory of the app.
+
+43
+00:03:36,000 --> 00:03:43,000
+That's why sometimes this query might come in handy, especially when you want to implement pagination.
+
+44
+00:03:43,000 --> 00:03:51,000
+A little bit later, we're going to talk about pagination, so to search items and database site, you
+
+45
+00:03:51,000 --> 00:03:55,000
+still use the same select statement, but you have to add order.
+
+46
+00:03:55,000 --> 00:04:01,000
+By the end of the query, you should specify column that you are going to use for searching.
+
+47
+00:04:02,000 --> 00:04:05,000
+By default, searching is in ascending order.
+
+48
+00:04:06,000 --> 00:04:12,000
+That's why usually you may need sorting order option if you are good with default sorting.
+
+49
+00:04:13,000 --> 00:04:20,000
+But if you want rows to be sorted in descending order, you have to specify this vividly.
+
+50
+00:04:20,000 --> 00:04:25,000
+You can source all the rows by two or more columns if needed.
+
+51
+00:04:26,000 --> 00:04:31,000
+Just list columns that you want to use for certain separate by comma.
+
+52
+00:04:31,000 --> 00:04:38,000
+Like in the example on the slide, you want to search all the rows by field one in descending order
+
+53
+00:04:39,000 --> 00:04:41,000
+and by field two in ascending order.
+
+54
+00:04:42,000 --> 00:04:50,000
+Besides selecting all roles with all fields, you can be more specific, for example, after select
+
+55
+00:04:50,000 --> 00:04:54,000
+keywords, you can least fields that you want to extract.
+
+56
+00:04:55,000 --> 00:04:59,000
+Also, you can put them close and specify select conditions.
+
+57
+00:05:00,000 --> 00:05:08,000
+In this case, we need to select all roles where field one has to be less than 10, and Field two has
+
+58
+00:05:08,000 --> 00:05:17,000
+to be equal to X and believe you are smart enough to understand the type of data query should match
+
+59
+00:05:17,000 --> 00:05:18,000
+was data type of the column.
+
+60
+00:05:19,000 --> 00:05:22,000
+You can use logical conjunction keywords.
+
+61
+00:05:23,000 --> 00:05:29,000
+You can use IZA and or or keywords when you use and do.
+
+62
+00:05:29,000 --> 00:05:38,000
+Conditions will be very in each Stacpoole and only zone is that much of these conditions will be returned.
+
+63
+00:05:38,000 --> 00:05:47,000
+If you use or that means that in case at least one of these conditions is Matt will return zero.
+
+64
+00:05:47,000 --> 00:05:55,000
+These are not the only logical operators a little bit later today in the lesson we are going to review
+
+65
+00:05:55,000 --> 00:05:57,000
+other operators too.
+
+66
+00:05:57,000 --> 00:06:05,000
+But I would say that most of the times you would use either and or or use every single year so far.
+
+67
+00:06:06,000 --> 00:06:12,000
+Remember that even in case you have any questions, you can always write them in the comments to this
+
+68
+00:06:12,000 --> 00:06:13,000
+video.
+
+69
+00:06:14,000 --> 00:06:20,000
+And if this small piece of theory is clear for you, that means we are going to proceed with real examples
+
+70
+00:06:20,000 --> 00:06:23,000
+and learning of you select statements.
+
+71
+00:06:24,000 --> 00:06:28,000
+Now let's execute these statements against data in database.
+
+72
+00:06:29,000 --> 00:06:34,000
+And as usual, I'm going to save all queries that will be used in this lesson.
+
+73
+00:06:34,000 --> 00:06:38,000
+And you will find them in attachments to the lesson.
+
+74
+00:06:38,000 --> 00:06:45,000
+Having the same queries will allow you to run the same queries on your own computer to understand as
+
+75
+00:06:45,000 --> 00:06:46,000
+a topic better.
+
+76
+00:06:47,000 --> 00:06:52,000
+Before we start execute queries, make sure that your previous lessons.
+
+77
+00:06:52,000 --> 00:06:56,000
+You also created user, themore the same as I did.
+
+78
+00:06:56,000 --> 00:07:00,000
+Also pay attention that we already pasted some information here.
+
+79
+00:07:01,000 --> 00:07:09,000
+I just changed the names and emails here to make it look more realistic because to be able to see how
+
+80
+00:07:09,000 --> 00:07:13,000
+select statements work, you have to have some data first.
+
+81
+00:07:13,000 --> 00:07:20,000
+So as you can see, the simplest query is to select all couples from user table, and it looks like
+
+82
+00:07:20,000 --> 00:07:23,000
+this nice and special and great.
+
+83
+00:07:24,000 --> 00:07:32,000
+If you want to extract on the specific fields, you should list them instead of asterisk, like I did
+
+84
+00:07:32,000 --> 00:07:34,000
+here in this particular example.
+
+85
+00:07:34,000 --> 00:07:38,000
+I want to extract on the first name and last name.
+
+86
+00:07:38,000 --> 00:07:43,000
+Let's sort now fills my last name in descending order.
+
+87
+00:07:43,000 --> 00:07:47,000
+And after that, my first name in descending order.
+
+88
+00:07:48,000 --> 00:07:52,000
+That is needed because we already have a few rows with the same last name.
+
+89
+00:07:53,000 --> 00:07:57,000
+Thus, searching only by last name won't be enough.
+
+90
+00:07:58,000 --> 00:08:02,000
+And we have to come up with additional rule for sorting.
+
+91
+00:08:02,000 --> 00:08:08,000
+I add order by keywords and specify columns that I want to use for sorting.
+
+92
+00:08:09,000 --> 00:08:10,000
+Let's execute this query.
+
+93
+00:08:11,000 --> 00:08:18,000
+Now, let's add condition I'd like to extract all rows where a last name is equal to Ivanov.
+
+94
+00:08:19,000 --> 00:08:22,000
+I write very close and specify condition.
+
+95
+00:08:23,000 --> 00:08:29,000
+And after we executed queries, we received only rows that meets our condition.
+
+96
+00:08:29,000 --> 00:08:34,000
+Regarding operators in my school, you can use different operators.
+
+97
+00:08:35,000 --> 00:08:42,000
+As I said, let's discuss operators as a separate topic and little bit later today, but ensured talking
+
+98
+00:08:42,000 --> 00:08:44,000
+about comparative operators.
+
+99
+00:08:44,000 --> 00:08:53,000
+NASA's special you can use more or less more or equal to less or equal to not equal to operators here
+
+100
+00:08:53,000 --> 00:08:53,000
+in condition.
+
+101
+00:08:54,000 --> 00:09:02,000
+One more important scene to show you is this certain keywords, for example, you need to extract all
+
+102
+00:09:02,000 --> 00:09:07,000
+different last names or names from the table without any duplicates.
+
+103
+00:09:07,000 --> 00:09:12,000
+You can use distinct keywords in the attribute to receive all the different values.
+
+104
+00:09:13,000 --> 00:09:19,000
+Like in this example, when we executed the query, we don't receive any duplicated last names.
+
+105
+00:09:19,000 --> 00:09:20,000
+Does it make sense?
+
+106
+00:09:21,000 --> 00:09:28,000
+Now, let's imagine that you forgot what you are looking for and you don't remember the search parameter.
+
+107
+00:09:29,000 --> 00:09:33,000
+But you remember that last name of the user you started from if.
+
+108
+00:09:34,000 --> 00:09:36,000
+How to find what you need.
+
+109
+00:09:36,000 --> 00:09:40,000
+You can search by specified pattern was like.
+
+110
+00:09:40,000 --> 00:09:41,000
+Operator.
+
+111
+00:09:41,000 --> 00:09:48,000
+The operator is used in a where close to search for a specified partner in the column.
+
+112
+00:09:49,000 --> 00:09:55,000
+There are two wild cards often used in conjunction with like operator Z.
+
+113
+00:09:55,000 --> 00:09:59,000
+Person Sign represents zero one or multiple characters.
+
+114
+00:09:59,000 --> 00:10:08,000
+The underscore sign represents one single character in our specific case one we want to find all rows
+
+115
+00:10:08,000 --> 00:10:14,000
+where our last name is started was safe and we don't know the full last name.
+
+116
+00:10:14,000 --> 00:10:16,000
+We need to use person sign.
+
+117
+00:10:17,000 --> 00:10:25,000
+Look at this query by this and telling us that after if there might be a different number of characters,
+
+118
+00:10:25,000 --> 00:10:28,000
+let's execute this first query.
+
+119
+00:10:28,000 --> 00:10:34,000
+And you can see that I have to tap those returns in as a query.
+
+120
+00:10:34,000 --> 00:10:39,000
+I am saying that zero is one character that is followed by me.
+
+121
+00:10:39,000 --> 00:10:45,000
+And after that, we have a different amount of characters, and I don't know how much.
+
+122
+00:10:45,000 --> 00:10:48,000
+Exactly opposite is it clear?
+
+123
+00:10:49,000 --> 00:10:56,000
+That's not what education nation is and what we need to know to support pagination on the database level,
+
+124
+00:10:57,000 --> 00:11:05,000
+pagination is a matter of divided content into discrete pages, thus presenting content in a limited
+
+125
+00:11:06,000 --> 00:11:07,000
+and digestible manner.
+
+126
+00:11:08,000 --> 00:11:16,000
+We will search result page is a typical example of such a search if you downloaded applications that
+
+127
+00:11:16,000 --> 00:11:19,000
+I created for my students, for mobile phones.
+
+128
+00:11:19,000 --> 00:11:20,000
+Learn it.
+
+129
+00:11:20,000 --> 00:11:24,000
+You can find the example of pagination in the history.
+
+130
+00:11:25,000 --> 00:11:33,000
+If you have a lot of tests and certifications passed and you open history inside the app to explore
+
+131
+00:11:33,000 --> 00:11:41,000
+your previous results, you can scroll test results, but not all test results extracted from the database
+
+132
+00:11:41,000 --> 00:11:42,000
+at once.
+
+133
+00:11:43,000 --> 00:11:47,000
+They are loaded in chunks after you scrolled to the lowest record.
+
+134
+00:11:48,000 --> 00:11:51,000
+I extracted records from a database by small chunks.
+
+135
+00:11:52,000 --> 00:11:59,000
+Instead of extracting all of the latest records at once during the stand, imagine that you have 100
+
+136
+00:11:59,000 --> 00:12:05,000
+or even 1000 test results, but you need to check on the few last ones.
+
+137
+00:12:05,000 --> 00:12:13,000
+In this case, is any sense to extract all rows and pass them from the server into the mobile app.
+
+138
+00:12:14,000 --> 00:12:15,000
+Definitely not.
+
+139
+00:12:15,000 --> 00:12:23,000
+That's why you're in the design of our app before we see that we need pagination support here and to
+
+140
+00:12:23,000 --> 00:12:26,000
+be even more specific in mobile apps.
+
+141
+00:12:26,000 --> 00:12:33,000
+This is called Infinite's crawl, and this allows you to scroll content down without any interruption.
+
+142
+00:12:34,000 --> 00:12:40,000
+Infinite scrolling is a functionality allowing users to scroll down a massive amount of information,
+
+143
+00:12:41,000 --> 00:12:48,000
+presenting it in easy to consume chunks and data is uploaded as you reached the lowest records on the
+
+144
+00:12:48,000 --> 00:12:49,000
+screen.
+
+145
+00:12:49,000 --> 00:12:55,000
+I'm sure you're faced with such design while using other apps in database.
+
+146
+00:12:55,000 --> 00:12:59,000
+We can support pagination by extracting specified range of records.
+
+147
+00:12:59,000 --> 00:13:06,000
+With the help of limit operator, the cycle limit close restricts how many rows are returned from a
+
+148
+00:13:06,000 --> 00:13:07,000
+query.
+
+149
+00:13:07,000 --> 00:13:14,000
+The syntax for the limit close represents how many requests you want to retrieve and starting from which
+
+150
+00:13:14,000 --> 00:13:22,000
+record, for example, you can use is a limit close to retrieves a top five users by number of coins.
+
+151
+00:13:23,000 --> 00:13:30,000
+Or you could extract the user starting from the six position to tance sorted by number of coins.
+
+152
+00:13:31,000 --> 00:13:36,000
+Zeleny The class is only compatible with the sequel select statement.
+
+153
+00:13:36,000 --> 00:13:40,000
+You can use a limit class in SQL Update statement.
+
+154
+00:13:40,000 --> 00:13:44,000
+For instance, your limit number must be positive.
+
+155
+00:13:45,000 --> 00:13:48,000
+Say you want to retrieve records from the bottom of the list.
+
+156
+00:13:49,000 --> 00:13:54,000
+You should use a sequel or buy statement to order them in descending order.
+
+157
+00:13:55,000 --> 00:13:57,000
+Then you should use any misstatement.
+
+158
+00:13:58,000 --> 00:14:01,000
+Let's learn how to work with limited statement on practice.
+
+159
+00:14:02,000 --> 00:14:03,000
+We have three requests here.
+
+160
+00:14:04,000 --> 00:14:09,000
+Let me extract two users sorted by email in ascending order.
+
+161
+00:14:09,000 --> 00:14:13,000
+I write Select all from user order by email.
+
+162
+00:14:14,000 --> 00:14:22,000
+Limit to the last four limit two means that it would return me to records only.
+
+163
+00:14:22,000 --> 00:14:27,000
+Let's execute this query, and you can see that where was these?
+
+164
+00:14:27,000 --> 00:14:30,000
+Three and four have been returned.
+
+165
+00:14:31,000 --> 00:14:35,000
+But as we have already discussed, we can specify offset.
+
+166
+00:14:35,000 --> 00:14:37,000
+We add additional parameter.
+
+167
+00:14:37,000 --> 00:14:46,000
+In the second example, offset is one, so we are skipping the first one returned and will return to
+
+168
+00:14:46,000 --> 00:14:48,000
+records after the first one.
+
+169
+00:14:48,000 --> 00:14:49,000
+Does it make sense?
+
+170
+00:14:50,000 --> 00:14:55,000
+So we return to records after keeping the first records?
+
+171
+00:14:55,000 --> 00:14:59,000
+Basically from the second position of our ordering.
+
+172
+00:15:00,000 --> 00:15:07,000
+And now when we execute this query, we have records with I.D. four and one return.
+
+173
+00:15:07,000 --> 00:15:15,000
+Is it clear for you why this is happening and when you implement queries for your app, you can build
+
+174
+00:15:15,000 --> 00:15:16,000
+them accordingly.
+
+175
+00:15:16,000 --> 00:15:23,000
+For example, you can post as a server parameters of pages that you want to retrieve and the number
+
+176
+00:15:23,000 --> 00:15:26,000
+of trackers and paste them into the query.
+
+177
+00:15:27,000 --> 00:15:29,000
+Anyways, this is not a topic of this lesson.
+
+178
+00:15:29,000 --> 00:15:34,000
+It is just a hint we'll learn how to implement this one.
+
+179
+00:15:34,000 --> 00:15:38,000
+We'll start learning of that application development as of now.
+
+180
+00:15:39,000 --> 00:15:43,000
+I want you to know and remember how to work with that statement.
+
+181
+00:15:44,000 --> 00:15:51,000
+The next thing that I'd like to amuse you is Quarians, and no attributes, just a smile or see them
+
+182
+00:15:51,000 --> 00:15:59,000
+then, but still very important, and a lot of my students do the same mistake when they just start
+
+183
+00:15:59,000 --> 00:16:00,000
+to use in school.
+
+184
+00:16:00,000 --> 00:16:08,000
+If you want to select couples that have no value in some of the attributes, you can just use equal
+
+185
+00:16:08,000 --> 00:16:09,000
+operator.
+
+186
+00:16:10,000 --> 00:16:16,000
+Let me show you if you want to select users is that's no value in the f k user all field.
+
+187
+00:16:17,000 --> 00:16:24,000
+You can't just use equal operator because it won't give you results that you expect.
+
+188
+00:16:24,000 --> 00:16:31,000
+Instead, you have to use another keyword you have to use is now or is not now.
+
+189
+00:16:31,000 --> 00:16:34,000
+This is a specific that you should be aware of.
+
+190
+00:16:35,000 --> 00:16:37,000
+So please don't forget about this.
+
+191
+00:16:38,000 --> 00:16:44,000
+We already removed a few examples, and I believe you understand how to work with select statements,
+
+192
+00:16:44,000 --> 00:16:49,000
+but still and those are things that we need to learn is different operators.
+
+193
+00:16:49,000 --> 00:16:53,000
+Definitely, there is no sense to hold them off.
+
+194
+00:16:53,000 --> 00:16:58,000
+Select statements on real data was each possible operator instead.
+
+195
+00:16:58,000 --> 00:17:02,000
+Problem is, there is a sense to learn different operators now.
+
+196
+00:17:02,000 --> 00:17:06,000
+I will also provide you with examples of how to apply different.
+
+197
+00:17:06,000 --> 00:17:12,000
+Operator Let's start from the first group of operators in sequel arithmetic operators.
+
+198
+00:17:13,000 --> 00:17:20,000
+Basically, there is nothing special and no signs that you didn't learn in elementary school.
+
+199
+00:17:20,000 --> 00:17:24,000
+The only exclusion is modular operator problem.
+
+200
+00:17:24,000 --> 00:17:30,000
+But if you are familiar with one of the most popular programming languages, you already knows that
+
+201
+00:17:30,000 --> 00:17:35,000
+usually person sign is used for operations to extract reminder after division.
+
+202
+00:17:36,000 --> 00:17:40,000
+If you need a few more seconds to review examples, please.
+
+203
+00:17:40,000 --> 00:17:41,000
+Grasset boss.
+
+204
+00:17:42,000 --> 00:17:43,000
+Let's continue.
+
+205
+00:17:43,000 --> 00:17:49,000
+Well, that was a group of operators that we are going to review its comparison operators.
+
+206
+00:17:49,000 --> 00:17:57,000
+Most of them are also familiar to you, probably not equal to operator may look like and you one for
+
+207
+00:17:57,000 --> 00:17:58,000
+some students.
+
+208
+00:17:59,000 --> 00:18:07,000
+Basically, the general rule is not equal to operator is written like this, but also in some relational
+
+209
+00:18:07,000 --> 00:18:08,000
+database management systems.
+
+210
+00:18:08,000 --> 00:18:15,000
+It is also possible to use another syntax of note equal to operator that is more similar to one that
+
+211
+00:18:15,000 --> 00:18:17,000
+we use in programming languages.
+
+212
+00:18:18,000 --> 00:18:25,000
+And on this slide, you can find logical operators will read your review to such logical operators as
+
+213
+00:18:25,000 --> 00:18:27,000
+and or lie.
+
+214
+00:18:28,000 --> 00:18:38,000
+But as you can see, some of them look through the table on this slide, grasp if needed, and ask questions
+
+215
+00:18:38,000 --> 00:18:42,000
+in comments to the video in case someone is still not clear here.
+
+216
+00:18:43,000 --> 00:18:50,000
+Now, let's learn aggregate functions again, then we'll use them with select statements.
+
+217
+00:18:50,000 --> 00:18:57,000
+That's why I believe it is better to use them in conjunction with select statements and aggregate function,
+
+218
+00:18:57,000 --> 00:19:06,000
+performs a calculation on a set of values and returns a single value except for count aggregate functions.
+
+219
+00:19:06,000 --> 00:19:08,000
+Ignore null values.
+
+220
+00:19:08,000 --> 00:19:15,000
+Aggregate functions are often used with the group by close of the select statement, and here in the
+
+221
+00:19:15,000 --> 00:19:22,000
+slide, you can see product table examples that I'm going to use for the explanation of the following
+
+222
+00:19:22,000 --> 00:19:23,000
+aggregate functions.
+
+223
+00:19:24,000 --> 00:19:26,000
+Let's start from the learned man and the.
+
+224
+00:19:27,000 --> 00:19:32,000
+Based on the name of these attribute functions, I believe it is easy to understand.
+
+225
+00:19:32,000 --> 00:19:39,000
+The first one returns minimal value in the column, and the second one returns the maximum value in
+
+226
+00:19:39,000 --> 00:19:39,000
+the column.
+
+227
+00:19:40,000 --> 00:19:45,000
+And on the slide, you can see example of queries executed against stable waste products.
+
+228
+00:19:46,000 --> 00:19:49,000
+We extract max and mean price.
+
+229
+00:19:50,000 --> 00:19:52,000
+The next aggregate function is count.
+
+230
+00:19:53,000 --> 00:19:59,000
+The count function returns a number of roles that matches a specified material.
+
+231
+00:19:59,000 --> 00:20:02,000
+You can also find query example on the slide.
+
+232
+00:20:03,000 --> 00:20:07,000
+The average function returns the average value of a number of column.
+
+233
+00:20:08,000 --> 00:20:12,000
+The sum function returns is a total sum of a number.
+
+234
+00:20:12,000 --> 00:20:14,000
+A column is everything clear.
+
+235
+00:20:15,000 --> 00:20:20,000
+Let's learn now group by keywords that are often used together with aggregate functions.
+
+236
+00:20:21,000 --> 00:20:28,000
+Zeiger by statement groups rows that have the same values in the summary rows, it is often used with
+
+237
+00:20:28,000 --> 00:20:29,000
+aggregate functions.
+
+238
+00:20:30,000 --> 00:20:35,000
+The group by statement groups rows that have the same values in the summary rose.
+
+239
+00:20:35,000 --> 00:20:43,000
+It is often used with aggregate functions like count marks mean some average subgroups, the results
+
+240
+00:20:43,000 --> 00:20:45,000
+said by one or more columns.
+
+241
+00:20:45,000 --> 00:20:47,000
+Let's reverse this on real demo.
+
+242
+00:20:48,000 --> 00:20:52,000
+We are going them a group by statement, an example of user table.
+
+243
+00:20:53,000 --> 00:20:57,000
+Let's find the most used a last name among our users.
+
+244
+00:20:58,000 --> 00:21:05,000
+We know that last name in our app is not unique and we want to understand how much users used the same
+
+245
+00:21:05,000 --> 00:21:06,000
+last name.
+
+246
+00:21:06,000 --> 00:21:13,000
+I want select total count of all rows and displays this count as a mount attribute.
+
+247
+00:21:13,000 --> 00:21:20,000
+And also, I want to extract the last name from user table and group results by a last name.
+
+248
+00:21:20,000 --> 00:21:22,000
+That's executed this query.
+
+249
+00:21:22,000 --> 00:21:26,000
+You can see that we have two people with even our last name.
+
+250
+00:21:26,000 --> 00:21:29,000
+And one user with Komarov last name.
+
+251
+00:21:29,000 --> 00:21:30,000
+And then the results.
+
+252
+00:21:30,000 --> 00:21:33,000
+That count has been returned as a mound column.
+
+253
+00:21:34,000 --> 00:21:41,000
+When I wrote this query, I used this error automatically because when you use aggregate functions,
+
+254
+00:21:41,000 --> 00:21:45,000
+you also ones that column would have meaningful name.
+
+255
+00:21:46,000 --> 00:21:47,000
+The syntax is simple.
+
+256
+00:21:47,000 --> 00:21:53,000
+You use ASCII words and specifies a desert attribute name, sequel aliases.
+
+257
+00:21:53,000 --> 00:21:58,000
+I used to give a table or column in the table at temporary name.
+
+258
+00:21:58,000 --> 00:22:05,000
+Aliases are often used to make column names more readable, and A. only exists for the duration of that
+
+259
+00:22:05,000 --> 00:22:11,000
+query and A. is created was SE keywords in my sequel.
+
+260
+00:22:11,000 --> 00:22:16,000
+I usually omit ASCII word and use else straight away.
+
+261
+00:22:17,000 --> 00:22:23,000
+We grouped our result by last name and managed to receive a result like this hobs.
+
+262
+00:22:23,000 --> 00:22:24,000
+This is clear now.
+
+263
+00:22:25,000 --> 00:22:33,000
+Another interesting saying that when you use group by keywords, you can apply condition to groups.
+
+264
+00:22:33,000 --> 00:22:39,000
+To do this, you have to use havant keywords in very, very simplified words.
+
+265
+00:22:39,000 --> 00:22:47,000
+Heaven is the same as where in regular select statements, the difference is that you can't apply where
+
+266
+00:22:47,000 --> 00:22:55,000
+after group by statement, because where is applied for each sample while reviewing each records, whereas
+
+267
+00:22:55,000 --> 00:22:58,000
+haven't may be applied to the group of tables.
+
+268
+00:22:58,000 --> 00:23:06,000
+Once we iterated over records in table workflows introduces a condition on individual rows, having
+
+269
+00:23:06,000 --> 00:23:09,000
+close introduces a condition on aggregations.
+
+270
+00:23:10,000 --> 00:23:13,000
+Does it make sense from human language?
+
+271
+00:23:13,000 --> 00:23:15,000
+We have few more important statements to learn.
+
+272
+00:23:16,000 --> 00:23:18,000
+Let's learn Insert statement.
+
+273
+00:23:18,000 --> 00:23:23,000
+Basically, this statement is used to insert new records in the table.
+
+274
+00:23:23,000 --> 00:23:32,000
+The general structure of insert statement looks like this insert into table name lists of columns where
+
+275
+00:23:32,000 --> 00:23:33,000
+you want to insert values.
+
+276
+00:23:34,000 --> 00:23:38,000
+After that, gross values, keyword and list of values.
+
+277
+00:23:39,000 --> 00:23:45,000
+This is the most common syntax of insert statement, but definitely is a resource a way to make simple
+
+278
+00:23:45,000 --> 00:23:47,000
+things more complex.
+
+279
+00:23:47,000 --> 00:23:48,000
+Just joking.
+
+280
+00:23:49,000 --> 00:23:55,000
+But indeed, there might be different variations of insert statements in attachments to the media.
+
+281
+00:23:55,000 --> 00:24:00,000
+You will find Link to the official documentation about insert statement in my sequel.
+
+282
+00:24:01,000 --> 00:24:07,000
+Xanax thinks that you have to remember about insert statements inserts, but suffice to table where
+
+283
+00:24:07,000 --> 00:24:11,000
+data will be inserted into we can omit column.
+
+284
+00:24:12,000 --> 00:24:19,000
+If a column is amended, each value must be provided if you include in columns that can be listed in
+
+285
+00:24:19,000 --> 00:24:25,000
+any order value specifies the data that you want to insert into the table.
+
+286
+00:24:26,000 --> 00:24:30,000
+Value is required in certain and I'm just throwing into a word.
+
+287
+00:24:30,000 --> 00:24:34,000
+Char Ortex column inserts a single space.
+
+288
+00:24:35,000 --> 00:24:43,000
+All trading spaces are removed from data inserted into large columns, except in strings that contain
+
+289
+00:24:43,000 --> 00:24:44,000
+only spaces.
+
+290
+00:24:44,000 --> 00:24:47,000
+This strings are truncated to a single space.
+
+291
+00:24:49,000 --> 00:24:57,000
+If an insert statement violates a constraint, default or rule, or if it is wrong data type, the statement
+
+292
+00:24:57,000 --> 00:25:01,000
+fails and sequels, server displays and error message.
+
+293
+00:25:02,000 --> 00:25:09,000
+Let's insert a few rows in our user table on the screen, you can see example often search query.
+
+294
+00:25:09,000 --> 00:25:16,000
+We want to insert the records, but tensions at one record has EFCC use a roll value specified.
+
+295
+00:25:17,000 --> 00:25:24,000
+And another record doesn't have the number of values should margins the number of columns we listed.
+
+296
+00:25:25,000 --> 00:25:32,000
+So let's execute the query insert statement or iTunes has a number of how many rows have been impacted.
+
+297
+00:25:32,000 --> 00:25:37,000
+After execution of this query, we impacted two rows in total.
+
+298
+00:25:37,000 --> 00:25:44,000
+Now we can select all rows in our user table and make sure that we inserted two records.
+
+299
+00:25:45,000 --> 00:25:46,000
+Is it clear?
+
+300
+00:25:47,000 --> 00:25:49,000
+If yes, then let's proceed.
+
+301
+00:25:49,000 --> 00:25:54,000
+The update statement is used to modify the existing records.
+
+302
+00:25:54,000 --> 00:25:56,000
+In the table is a general query.
+
+303
+00:25:56,000 --> 00:25:58,000
+Structure looks like this.
+
+304
+00:25:58,000 --> 00:26:00,000
+You start with update keywords.
+
+305
+00:26:01,000 --> 00:26:08,000
+After that specified table name after set keywords, we need to list pairs of column name and related
+
+306
+00:26:08,000 --> 00:26:09,000
+value.
+
+307
+00:26:09,000 --> 00:26:10,000
+Separate was comma.
+
+308
+00:26:11,000 --> 00:26:17,000
+Optionally, we can specify where a close to select rules that we want to accommodate and we can apply
+
+309
+00:26:17,000 --> 00:26:18,000
+limit.
+
+310
+00:26:19,000 --> 00:26:27,000
+The where clause, if given, specifies the conditions, is that identify which rose to update with
+
+311
+00:26:27,000 --> 00:26:28,000
+nowhere close.
+
+312
+00:26:28,000 --> 00:26:33,000
+All the rules are updated if the order by clause is specified.
+
+313
+00:26:34,000 --> 00:26:42,000
+Zero's updated in the order that a specified the limit clause places a limit on the number of rules
+
+314
+00:26:42,000 --> 00:26:43,000
+that can be updated.
+
+315
+00:26:44,000 --> 00:26:50,000
+In our example, we decided to change email for our user and assign new role for him.
+
+316
+00:26:51,000 --> 00:26:58,000
+An example you can see that I assign new value to email attribute and to f k user role attribute.
+
+317
+00:26:59,000 --> 00:27:05,000
+I use very close to update on the one row I have unique identifier in this table.
+
+318
+00:27:05,000 --> 00:27:08,000
+That's why, in workflows, I use ID.
+
+319
+00:27:09,000 --> 00:27:17,000
+Let me execute this squaring I'mnot statement also returns a number of updated throws with successfully
+
+320
+00:27:17,000 --> 00:27:18,000
+updated one rule.
+
+321
+00:27:18,000 --> 00:27:23,000
+We can check our table to make sure that email and foreign key value is changed.
+
+322
+00:27:24,000 --> 00:27:27,000
+If everything is clear, then let's move on.
+
+323
+00:27:28,000 --> 00:27:34,000
+And the last, but not least for today, the lead statement, the statement is used to delete existing
+
+324
+00:27:34,000 --> 00:27:35,000
+records in the table.
+
+325
+00:27:36,000 --> 00:27:43,000
+One important thing to mention here is that in case you would admit where close, you would remove all
+
+326
+00:27:43,000 --> 00:27:45,000
+records from the table.
+
+327
+00:27:45,000 --> 00:27:48,000
+So be very attentive with this query.
+
+328
+00:27:49,000 --> 00:27:54,000
+According to documentation, you can also use or them by and limit the keywords.
+
+329
+00:27:55,000 --> 00:27:58,000
+In that example, we decided to remove one row.
+
+330
+00:27:58,000 --> 00:28:04,000
+Here is how it look like I specified three of the role that I want to remove.
+
+331
+00:28:05,000 --> 00:28:06,000
+Let's execute this query.
+
+332
+00:28:07,000 --> 00:28:13,000
+And you can see in logs that the lead statement also returns number of rows that were impacted with
+
+333
+00:28:13,000 --> 00:28:13,000
+this query.
+
+334
+00:28:14,000 --> 00:28:17,000
+That's all I wanted to share with you in this lesson.
+
+335
+00:28:17,000 --> 00:28:19,000
+Let's recap what we have learned today.
+
+336
+00:28:20,000 --> 00:28:26,000
+In this lesson, we learned select statements, I showed you select statements with different options,
+
+337
+00:28:27,000 --> 00:28:35,000
+including selecting Rose is ordering wear clothes, distinct selection search by pardon Lehman's a number
+
+338
+00:28:35,000 --> 00:28:39,000
+of rose to be returned grouping and the blind condition on groups.
+
+339
+00:28:40,000 --> 00:28:43,000
+You learned different skill operators.
+
+340
+00:28:44,000 --> 00:28:48,000
+Now you know what aggregate functions are and how to work with them.
+
+341
+00:28:48,000 --> 00:28:52,000
+I showed you how to work with others in school.
+
+342
+00:28:52,000 --> 00:28:57,000
+And also, we discussed insert, update and delete statements.
+
+343
+00:28:58,000 --> 00:28:59,000
+That's all for this lesson.
+
+344
+00:29:00,000 --> 00:29:02,000
+Thanks a lot for your attention.
+
+345
+00:29:02,000 --> 00:29:05,000
+Have a great day and see you in the next lesson.
+

48 - SQL/003 JOIN Queries, UNION & Subqueries_en.srt

@@ -0,0 +1,732 @@
+1
+00:00:06,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:06,000 --> 00:00:12,000
+In this lesson, we continue to learn sequel and will focus on such important group of queries as joint
+
+3
+00:00:12,000 --> 00:00:13,000
+queries.
+
+4
+00:00:13,000 --> 00:00:19,000
+Considering the fact we are dealing with relational databases very often we have to create joint queries
+
+5
+00:00:19,000 --> 00:00:20,000
+to multiple tables.
+
+6
+00:00:21,000 --> 00:00:26,000
+And also, we are going to review a few more SQL statements that I didn't cover in previous lesson plans
+
+7
+00:00:26,000 --> 00:00:27,000
+that are too small.
+
+8
+00:00:27,000 --> 00:00:33,000
+For a separate lesson in the lesson, we'll put our focus on Jones sequel statements.
+
+9
+00:00:33,000 --> 00:00:42,000
+We're going to review different types of June queries that includes in the left right cross and full
+
+10
+00:00:42,000 --> 00:00:43,000
+order giants.
+
+11
+00:00:43,000 --> 00:00:47,000
+I also prepare examples for each case to review Is you?
+
+12
+00:00:47,000 --> 00:00:53,000
+You will be able to find all examples that will review each lesson in attachments to the veto.
+
+13
+00:00:54,000 --> 00:01:00,000
+Also, we are going to learn union keyword and understand how it works and that sense of the lesson.
+
+14
+00:01:00,000 --> 00:01:04,000
+I will teach you how to construct queries with sub queries.
+
+15
+00:01:05,000 --> 00:01:06,000
+Let's start our lesson.
+
+16
+00:01:07,000 --> 00:01:12,000
+I believe that you already understood that in relational databases, we split data between different
+
+17
+00:01:12,000 --> 00:01:16,000
+tables and apply normalization with data redundancy.
+
+18
+00:01:17,000 --> 00:01:25,000
+This means that to extract data that you need, sometimes you need to execute so-called joint queries
+
+19
+00:01:25,000 --> 00:01:33,000
+against not one, but multiple tables in step joint query commands, columns from one or more tables
+
+20
+00:01:33,000 --> 00:01:42,000
+into a new table and see standard sequels insofar as five types of joy in the left order, right order,
+
+21
+00:01:42,000 --> 00:01:44,000
+food order and cross.
+
+22
+00:01:45,000 --> 00:01:50,000
+Let's learn how these joints look in theory, and after that, we review practice examples.
+
+23
+00:01:51,000 --> 00:01:58,000
+Further examples will be shown considering these two tables user and role that actions at user table
+
+24
+00:01:58,000 --> 00:02:06,000
+contains foreign key to role table and also Xerri users without rules and also the roles that are not
+
+25
+00:02:06,000 --> 00:02:08,000
+assigned to any user.
+
+26
+00:02:09,000 --> 00:02:14,000
+The same tables I have in my school, we created zones during the previous lessons.
+
+27
+00:02:15,000 --> 00:02:19,000
+If you want to repeat queries after me, make sure you have the same tables.
+
+28
+00:02:20,000 --> 00:02:28,000
+The best visualization of Junqueras is these two circles your circles represent the set of records that
+
+29
+00:02:28,000 --> 00:02:29,000
+exist in two tables.
+
+30
+00:02:30,000 --> 00:02:36,000
+Basically, you can see that one table is on the left and another table is on the right.
+
+31
+00:02:36,000 --> 00:02:44,000
+That tangent that these two circles have intersection zigzag in the records is it can be mapped between
+
+32
+00:02:44,000 --> 00:02:45,000
+each other.
+
+33
+00:02:45,000 --> 00:02:54,000
+In simple words, the area inside these two circles is called in a joint area that includes space without
+
+34
+00:02:54,000 --> 00:02:55,000
+intersection.
+
+35
+00:02:55,000 --> 00:02:58,000
+It's called the left and right or the John.
+
+36
+00:02:59,000 --> 00:03:06,000
+Anyway, we're going to review each of you and type on real examples and one by one, and let's start
+
+37
+00:03:06,000 --> 00:03:07,000
+from Injune.
+
+38
+00:03:07,000 --> 00:03:14,000
+You can imagine it as an intersection between two tables and enjoying requires each row in the two joints
+
+39
+00:03:14,000 --> 00:03:17,000
+tables to have matching column values.
+
+40
+00:03:18,000 --> 00:03:25,000
+This is exactly the moment when we'll use our foreign keys to establish connections between tables in
+
+41
+00:03:25,000 --> 00:03:27,000
+a joint creates and result table.
+
+42
+00:03:27,000 --> 00:03:35,000
+By combining column values of two tables based upon the joint predicate, imagine that we have two tables.
+
+43
+00:03:35,000 --> 00:03:37,000
+Z are A and B.
+
+44
+00:03:37,000 --> 00:03:47,000
+Table Zucchero compares each row of a with each row of D to find all pairs of rows that satisfy the
+
+45
+00:03:47,000 --> 00:03:49,000
+joint pretty good ones.
+
+46
+00:03:49,000 --> 00:03:52,000
+A joint project is satisfied by matching non low values.
+
+47
+00:03:52,000 --> 00:03:59,000
+Common values for each pair of rows of A and B are combined into result.
+
+48
+00:03:59,000 --> 00:04:08,000
+Row six specifies two different syntactical ways to express joints z explicit joint notation and same
+
+49
+00:04:08,000 --> 00:04:14,000
+place adjourn notation simply to join notation is no longer considered the best practice.
+
+50
+00:04:14,000 --> 00:04:17,000
+Also, database system still supported.
+
+51
+00:04:17,000 --> 00:04:26,000
+The explicit annotation uses a joint keyword optionally preceded by a keyword to specify the table to
+
+52
+00:04:26,000 --> 00:04:30,000
+join and the only keyword to specify the precursor for the joint.
+
+53
+00:04:31,000 --> 00:04:34,000
+Today, we're going to review a different query examples.
+
+54
+00:04:35,000 --> 00:04:36,000
+I save all of them.
+
+55
+00:04:36,000 --> 00:04:40,000
+You will be able to find those in attachments to this lesson.
+
+56
+00:04:41,000 --> 00:04:45,000
+Let me show you a demo of in our John Kerry just to remind you.
+
+57
+00:04:45,000 --> 00:04:48,000
+Here is how our user table looks like.
+
+58
+00:04:48,000 --> 00:04:50,000
+Not all users have role.
+
+59
+00:04:51,000 --> 00:04:53,000
+And here's how our old table looks like.
+
+60
+00:04:54,000 --> 00:04:59,000
+Zero rules that are not a science None of the users is that clear.
+
+61
+00:05:00,000 --> 00:05:06,000
+Now let's select last name and role name of all users with their roles.
+
+62
+00:05:06,000 --> 00:05:11,000
+We will not take into account users without rows and rows without users.
+
+63
+00:05:12,000 --> 00:05:16,000
+I write select fields that they need and their attention.
+
+64
+00:05:16,000 --> 00:05:21,000
+I use tables on us to specify which fields from each table I want to extract.
+
+65
+00:05:22,000 --> 00:05:26,000
+After that, I write from users table and pay attention.
+
+66
+00:05:26,000 --> 00:05:34,000
+I specify August here you is just a character that seems for me to be good as an alias for this table.
+
+67
+00:05:35,000 --> 00:05:42,000
+Basically, you last name in our query is a reference to the last name field in user table.
+
+68
+00:05:43,000 --> 00:05:43,000
+Is it clear?
+
+69
+00:05:44,000 --> 00:05:52,000
+After that, I right join Kyra, as we discussed, I can admit you, Akiva, and specify tables that
+
+70
+00:05:52,000 --> 00:05:58,000
+I want to join again and ask for old table is specified next to the role table name.
+
+71
+00:05:59,000 --> 00:06:05,000
+And after that, I need to specify what rule will be used for my records in two different tables.
+
+72
+00:06:06,000 --> 00:06:10,000
+That's why I write on key word and specifies the rule.
+
+73
+00:06:11,000 --> 00:06:17,000
+I do field from rule table should match with the f k zero field from user table.
+
+74
+00:06:17,000 --> 00:06:23,000
+If you followed your course and you didn't miss previous lessons, you should remember that f k is a
+
+75
+00:06:23,000 --> 00:06:25,000
+rule is a foreign key.
+
+76
+00:06:26,000 --> 00:06:33,000
+Now, I am sure that this query will return US ballot information that's executable, and we see two
+
+77
+00:06:33,000 --> 00:06:39,000
+rows return on the last name and roll like we requested any questions.
+
+78
+00:06:39,000 --> 00:06:40,000
+So 14.
+
+79
+00:06:40,000 --> 00:06:45,000
+In case of any questions, please read them in comments below this video.
+
+80
+00:06:46,000 --> 00:06:48,000
+Now, let's discuss Order Jones.
+
+81
+00:06:49,000 --> 00:06:57,000
+So how is this author joining verbs, the Jones table three themes each row, even if no awesome marching
+
+82
+00:06:57,000 --> 00:06:58,000
+rule exists.
+
+83
+00:06:58,000 --> 00:07:07,000
+All author joins Subdivide further into left joints, writes joints and full order joints based on which
+
+84
+00:07:07,000 --> 00:07:09,000
+tables throw you would like to retain.
+
+85
+00:07:10,000 --> 00:07:13,000
+How to understand where is that and where is right table?
+
+86
+00:07:14,000 --> 00:07:21,000
+It depends on which side from joint keyword the name is specified as a result of left or the joint or
+
+87
+00:07:21,000 --> 00:07:22,000
+simply left.
+
+88
+00:07:22,000 --> 00:07:24,000
+Join for tables.
+
+89
+00:07:24,000 --> 00:07:32,000
+A and B always contains all rows of the lap table, even if the joint condition doesn't find any metric
+
+90
+00:07:32,000 --> 00:07:33,000
+row in the right table.
+
+91
+00:07:34,000 --> 00:07:41,000
+This means that these are all close matches, zero rows in the right table for a given row in the left
+
+92
+00:07:41,000 --> 00:07:41,000
+table.
+
+93
+00:07:42,000 --> 00:07:49,000
+The joint will still return a row in the result, but with no in each column from the right table and
+
+94
+00:07:49,000 --> 00:07:51,000
+left or the joint returns.
+
+95
+00:07:51,000 --> 00:07:59,000
+All the values from an integer plus all values in the left table that do not match through the right
+
+96
+00:07:59,000 --> 00:08:03,000
+table, including rows, was now well used in Zelinka column.
+
+97
+00:08:04,000 --> 00:08:09,000
+Is it clear the same principle applies to the right auto joint?
+
+98
+00:08:09,000 --> 00:08:16,000
+But in this case, we return all records from inner joint plus all records from right the bill, even
+
+99
+00:08:16,000 --> 00:08:23,000
+if they don't match to any record in left table and the last stop of order, John is full order junk
+
+100
+00:08:24,000 --> 00:08:32,000
+conceptual at full auto joint combines the effect of applying both left and right, or the joints and
+
+101
+00:08:32,000 --> 00:08:37,000
+throws that don't have Malcolm in the table will have no values in the result set.
+
+102
+00:08:38,000 --> 00:08:41,000
+Let's now review these types of joints one real example.
+
+103
+00:08:42,000 --> 00:08:43,000
+Let's start from the left, Joan.
+
+104
+00:08:44,000 --> 00:08:51,000
+Basically, we would take the same queries that we reviewed neurons in the demo and will add left keema.
+
+105
+00:08:52,000 --> 00:08:55,000
+Let's execute it now and see what will be returned.
+
+106
+00:08:56,000 --> 00:09:04,000
+And you can see that we received all last means from our user table that is on the left from joint keyword
+
+107
+00:09:04,000 --> 00:09:08,000
+and for records where any match wasn't found in row table.
+
+108
+00:09:09,000 --> 00:09:13,000
+We just returned now that's called left joint right.
+
+109
+00:09:13,000 --> 00:09:20,000
+June would look opposite way in this case, which on all road names, even if we don't have users assigned
+
+110
+00:09:20,000 --> 00:09:28,000
+to this row because the table is on the right from June Cleaver and this is right joint query, does
+
+111
+00:09:28,000 --> 00:09:29,000
+it make sense?
+
+112
+00:09:30,000 --> 00:09:32,000
+Now, let me show you a question.
+
+113
+00:09:32,000 --> 00:09:38,000
+We just remove credit cards and leave on the John Key take into account.
+
+114
+00:09:38,000 --> 00:09:42,000
+We have four records in user table and four records in Table.
+
+115
+00:09:43,000 --> 00:09:46,000
+We're going to receive in total 16 records.
+
+116
+00:09:46,000 --> 00:09:52,000
+Basically, each records from one table should be mapped was each row from another table.
+
+117
+00:09:53,000 --> 00:09:57,000
+We receive all possible combinations of wrappers from each table.
+
+118
+00:09:57,000 --> 00:10:04,000
+To be honest, this type of query is interesting to know from series side, but probably it has limited
+
+119
+00:10:04,000 --> 00:10:06,000
+areas for use in in business cases.
+
+120
+00:10:06,000 --> 00:10:11,000
+It is rare seeing when you need to find combinations between all records from two tables.
+
+121
+00:10:12,000 --> 00:10:16,000
+And the last but not least type of joint is full order.
+
+122
+00:10:17,000 --> 00:10:20,000
+In my school, it can be implemented with the help of union keyword.
+
+123
+00:10:21,000 --> 00:10:23,000
+What is Union Keyword?
+
+124
+00:10:23,000 --> 00:10:27,000
+It combines two queries in one single query to the database.
+
+125
+00:10:27,000 --> 00:10:32,000
+In our case, we need to combine two queries with two joints left and right.
+
+126
+00:10:32,000 --> 00:10:35,000
+And you can see that I connect to select statements.
+
+127
+00:10:35,000 --> 00:10:43,000
+Was Union Kuvira that's executed this query, and we can see that we received all full records from
+
+128
+00:10:43,000 --> 00:10:49,000
+user table and all four records from the row table, even despite not all the records have mapping.
+
+129
+00:10:50,000 --> 00:10:52,000
+This makes sense homes.
+
+130
+00:10:52,000 --> 00:10:53,000
+It's now with this example.
+
+131
+00:10:53,000 --> 00:10:58,000
+Things become clearer and we also learned how union works.
+
+132
+00:10:59,000 --> 00:11:03,000
+Usually, union is used when you are dealing with some archived data.
+
+133
+00:11:03,000 --> 00:11:11,000
+When you queries a main table and operational or table was archived data regarding joints important
+
+134
+00:11:11,000 --> 00:11:16,000
+things to know that in this way, you can join two and more tables.
+
+135
+00:11:17,000 --> 00:11:20,000
+This will become important when you will come to the homework task.
+
+136
+00:11:21,000 --> 00:11:24,000
+Imagines that you are dealing with many, many relationships.
+
+137
+00:11:24,000 --> 00:11:29,000
+In this case, you have three tables that the disconnect between each other.
+
+138
+00:11:29,000 --> 00:11:31,000
+This will be part of your home desk.
+
+139
+00:11:32,000 --> 00:11:35,000
+I will also provide you with solutions as a home task.
+
+140
+00:11:35,000 --> 00:11:39,000
+But I just want you to solve this task by itself first.
+
+141
+00:11:39,000 --> 00:11:44,000
+The only one more topics that I'd love to discuss with you today is sub queries.
+
+142
+00:11:44,000 --> 00:11:49,000
+This topic is too small for a separate lesson, but still important to know.
+
+143
+00:11:49,000 --> 00:11:51,000
+I want to explain some queries.
+
+144
+00:11:52,000 --> 00:11:56,000
+What if you would like to create condition was the result of another query.
+
+145
+00:11:57,000 --> 00:11:59,000
+You can do so with the help of sub queries.
+
+146
+00:12:00,000 --> 00:12:04,000
+A sub query is a sequel query nested inside a logic query.
+
+147
+00:12:05,000 --> 00:12:12,000
+Sub query is also called and even a query or in there, so that while the statements contained in the
+
+148
+00:12:12,000 --> 00:12:21,000
+sub query is also called an auto query or to select the inner query executes first before its parent
+
+149
+00:12:21,000 --> 00:12:27,000
+query so that the results of an inner query can be passed to the auto query.
+
+150
+00:12:28,000 --> 00:12:33,000
+You can use a sub query in a select insert, delete or update statements.
+
+151
+00:12:33,000 --> 00:12:39,000
+A sub query is usually added within the very close of another SQL select statement.
+
+152
+00:12:39,000 --> 00:12:45,000
+In our particular example, let's imagine that we want to extract users who have value in money column
+
+153
+00:12:45,000 --> 00:12:53,000
+more than average money value across all users before you would be able to execute this kind of query.
+
+154
+00:12:53,000 --> 00:12:56,000
+Let's make small adjustments in our tables.
+
+155
+00:12:56,000 --> 00:13:02,000
+I need to add money column and fill it out with data to make your life easier.
+
+156
+00:13:03,000 --> 00:13:08,000
+I prepared script for you that would add new column and populated with data.
+
+157
+00:13:09,000 --> 00:13:13,000
+I am going to leave the reference to this script in attachments to this lesson.
+
+158
+00:13:14,000 --> 00:13:19,000
+If you follow the course and you have the same structure, script will be executed without problem.
+
+159
+00:13:20,000 --> 00:13:28,000
+Pay attention to the data type of money column 15 mins amount of decimal digits and two means that only
+
+160
+00:13:28,000 --> 00:13:30,000
+two digits after point will be supported.
+
+161
+00:13:30,000 --> 00:13:38,000
+Considering mass around and rules, OK, so once you executed this script, your user table should look
+
+162
+00:13:38,000 --> 00:13:39,000
+like this.
+
+163
+00:13:40,000 --> 00:13:43,000
+Now let me damari you how sub query works.
+
+164
+00:13:44,000 --> 00:13:46,000
+We create regular select statements.
+
+165
+00:13:46,000 --> 00:13:52,000
+We want to receive rows where money is more than average money amount, and that counts of all users.
+
+166
+00:13:53,000 --> 00:13:59,000
+For this, I need to execute this sub query first understands the amount of money that can be used.
+
+167
+00:13:59,000 --> 00:14:03,000
+In my order query, I put Sequeira in parentheses.
+
+168
+00:14:04,000 --> 00:14:05,000
+Let's execute this query.
+
+169
+00:14:06,000 --> 00:14:13,000
+Our money amount was this specific test data will be around five hundred sixty four and we have two
+
+170
+00:14:13,000 --> 00:14:19,000
+rows returns with money amount higher as an average money amount than this.
+
+171
+00:14:19,000 --> 00:14:22,000
+Now you can work with sub queries.
+
+172
+00:14:23,000 --> 00:14:23,000
+That's all.
+
+173
+00:14:23,000 --> 00:14:24,000
+What I wanted to share.
+
+174
+00:14:24,000 --> 00:14:25,000
+Was you in this lesson?
+
+175
+00:14:26,000 --> 00:14:28,000
+Let's recap what we have learned today.
+
+176
+00:14:29,000 --> 00:14:36,000
+This lesson we learned what joints are after that we focus on different joint types moving around in
+
+177
+00:14:36,000 --> 00:14:40,000
+the water, across joints and reviewed SQL queries.
+
+178
+00:14:41,000 --> 00:14:47,000
+Now you know how to work with union keywords, and the answers will have some of you learned how to
+
+179
+00:14:47,000 --> 00:14:48,000
+work with subwoofers.
+
+180
+00:14:49,000 --> 00:14:50,000
+That's all for this lesson.
+
+181
+00:14:50,000 --> 00:14:52,000
+Thanks a lot for your attention.
+
+182
+00:14:52,000 --> 00:14:53,000
+Have a great day.
+
+183
+00:14:54,000 --> 00:14:55,000
+See you next lesson.
+

48 - SQL/003 Query-Examples-that-were-shown-in-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/dml/joins

48 - SQL/external-links.txt

@@ -0,0 +1,15 @@
+
+001 MySQL-Documentation-about-statements
+https://dev.mysql.com/doc/refman/8.0/en/create-view.html
+
+001 Query-Examples-that-were-shown-in-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/ddl
+
+002 INSERT-statement-documentation
+https://dev.mysql.com/doc/refman/8.0/en/insert.html
+
+002 Query-Examples-that-were-shown-in-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/dml
+
+003 Query-Examples-that-were-shown-in-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/dml/joins

49 - Relational Databases (Advanced)/001 Find-folders-with-Views-Triggers-Stored-Procedures-and-Stored-Functions-SQL-query-examples-here.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/ddl

49 - Relational Databases (Advanced)/001 Views, Triggers, Stored Procedures & Functions_en.srt

@@ -0,0 +1,1548 @@
+1
+00:00:06,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:06,000 --> 00:00:11,000
+And this last one, we're going to learn some new concepts in a relational databases.
+
+3
+00:00:11,000 --> 00:00:16,000
+I would explain what use triggers, stored procedures and stored functions are.
+
+4
+00:00:16,000 --> 00:00:23,000
+Also, you will understand why we need them and how to work with them on practice, because today will
+
+5
+00:00:23,000 --> 00:00:24,000
+have practical part, too.
+
+6
+00:00:25,000 --> 00:00:27,000
+So be prepared for interesting lesson.
+
+7
+00:00:28,000 --> 00:00:30,000
+We are going to go over each topic.
+
+8
+00:00:30,000 --> 00:00:37,000
+One by one and one will focus on practical examples of use triggers, stored procedures and storage
+
+9
+00:00:37,000 --> 00:00:37,000
+functions.
+
+10
+00:00:38,000 --> 00:00:44,000
+I'm going also to explain just some new syntax features like, for example, single line and multi line
+
+11
+00:00:44,000 --> 00:00:47,000
+commonsensical session variables.
+
+12
+00:00:47,000 --> 00:00:53,000
+Also, I'll show you how you can change the limiter between SQL statements in my signal.
+
+13
+00:00:53,000 --> 00:00:55,000
+Let's start our lesson.
+
+14
+00:00:55,000 --> 00:00:59,000
+And the first thing that I'd like to review with you in this video is viewed.
+
+15
+00:01:00,000 --> 00:01:03,000
+Let's understand first what is viewed in databases.
+
+16
+00:01:04,000 --> 00:01:06,000
+We use virtual tables.
+
+17
+00:01:06,000 --> 00:01:10,000
+There are only a structure and contain no data.
+
+18
+00:01:10,000 --> 00:01:15,000
+Their purpose is to allow a user to see a subset of the actual data.
+
+19
+00:01:16,000 --> 00:01:20,000
+You can consist of a subset of one or more tables.
+
+20
+00:01:20,000 --> 00:01:25,000
+What might be the reasons for creating and use zero might be different reasons.
+
+21
+00:01:26,000 --> 00:01:28,000
+Among the advantages of using the use, it is worse.
+
+22
+00:01:28,000 --> 00:01:31,000
+Dimension restricts the view of a table.
+
+23
+00:01:32,000 --> 00:01:39,000
+For example, you can create a view that contains not all fields, but only some of them that don't
+
+24
+00:01:39,000 --> 00:01:40,000
+have any sensitive data.
+
+25
+00:01:41,000 --> 00:01:48,000
+So you can hide some of columns in tables in larger organizations where many developers may be working
+
+26
+00:01:48,000 --> 00:01:49,000
+on a project.
+
+27
+00:01:49,000 --> 00:01:54,000
+We use allowed developers to access unused data they need.
+
+28
+00:01:55,000 --> 00:02:03,000
+June two or more tables and show it as one object to use it instead of constantly right in June, Junqueras,
+
+29
+00:02:03,000 --> 00:02:11,000
+you can create value for most often joins and lets user to watch the whole attributes as one database
+
+30
+00:02:11,000 --> 00:02:11,000
+object.
+
+31
+00:02:12,000 --> 00:02:19,000
+This also simplify life of developers, restricts the access of a table so that nobody can insert zeros
+
+32
+00:02:19,000 --> 00:02:23,000
+into the table is every single year so far.
+
+33
+00:02:23,000 --> 00:02:30,000
+Let's look at examples who you watched previous lessons because in this lesson, we're going to use
+
+34
+00:02:30,000 --> 00:02:33,000
+tables that were created during the course.
+
+35
+00:02:33,000 --> 00:02:37,000
+We're going to create value with you and configure it for our needs.
+
+36
+00:02:38,000 --> 00:02:44,000
+We'll create a view from my school workbench, I'm going to show you sequel queries it will create for
+
+37
+00:02:44,000 --> 00:02:52,000
+you, for us just to remind you, we have two tables here user table and roll table here.
+
+38
+00:02:52,000 --> 00:02:58,000
+How's it look like this great view with user email and droll name?
+
+39
+00:02:58,000 --> 00:03:04,000
+Because this is a dataset I use most often in my app urines and log in.
+
+40
+00:03:04,000 --> 00:03:10,000
+I use user email and also I need to understand user role to use this information for further interaction
+
+41
+00:03:10,000 --> 00:03:12,000
+inside our app.
+
+42
+00:03:12,000 --> 00:03:19,000
+That's why it might be a good year for me to create this view and simplify life of developers to let
+
+43
+00:03:19,000 --> 00:03:19,000
+them.
+
+44
+00:03:19,000 --> 00:03:23,000
+Where is this for you directly instead of creation on Junqueras?
+
+45
+00:03:24,000 --> 00:03:29,000
+And I believe you understood that this is a simple example was two tables only.
+
+46
+00:03:29,000 --> 00:03:37,000
+But in real life, you might create tables that use junk, whereas the five or even more tables, we
+
+47
+00:03:37,000 --> 00:03:44,000
+are going to start simple and let's create this view for two attributes from the tables.
+
+48
+00:03:45,000 --> 00:03:50,000
+The grades have you in my school workbench, I can click on the Create View icon.
+
+49
+00:03:50,000 --> 00:03:57,000
+Technically speaking, my school workbench just help us was one learn or create you statement and after
+
+50
+00:03:57,000 --> 00:04:01,000
+--, we need to specify sequel query for all of you.
+
+51
+00:04:02,000 --> 00:04:06,000
+I click Apply button and I execute this query.
+
+52
+00:04:06,000 --> 00:04:12,000
+Now the great I love you and you can find it here and the use in my school workbench.
+
+53
+00:04:13,000 --> 00:04:20,000
+Basically, you can perform select operations against this view is the same as you do against a table
+
+54
+00:04:21,000 --> 00:04:22,000
+in select statement.
+
+55
+00:04:22,000 --> 00:04:24,000
+You just use your name.
+
+56
+00:04:25,000 --> 00:04:27,000
+Let me now update our regional tables.
+
+57
+00:04:28,000 --> 00:04:33,000
+For example, let's paste one more record in user table was role assigned.
+
+58
+00:04:36,000 --> 00:04:42,000
+One rule is that it lets execute, select all query to our view one more time.
+
+59
+00:04:43,000 --> 00:04:45,000
+And you can see that view is also updated.
+
+60
+00:04:46,000 --> 00:04:47,000
+Isn't that cool?
+
+61
+00:04:48,000 --> 00:04:50,000
+And you don't need to constantly read joint statements.
+
+62
+00:04:51,000 --> 00:04:55,000
+Pay attention that I can't add new rules here in view.
+
+63
+00:04:55,000 --> 00:05:00,000
+So as we discussed, we often use views for select statements.
+
+64
+00:05:01,000 --> 00:05:03,000
+That's all what I wanted to share with you regarding the use.
+
+65
+00:05:04,000 --> 00:05:05,000
+Is it clear?
+
+66
+00:05:06,000 --> 00:05:12,000
+Even in the case you have any questions, please add them in comments below this video, and I will
+
+67
+00:05:12,000 --> 00:05:13,000
+be happy to answer.
+
+68
+00:05:14,000 --> 00:05:16,000
+Let's proceed with a new topic.
+
+69
+00:05:17,000 --> 00:05:24,000
+That's what triggers are and how we can use them, and trigger is a set of instructions that are automatically
+
+70
+00:05:24,000 --> 00:05:30,000
+activated in response to a specific event occurred on a table in the database.
+
+71
+00:05:30,000 --> 00:05:34,000
+The trigger is always associated with a particular table.
+
+72
+00:05:34,000 --> 00:05:39,000
+If the table is deleted, all the associated triggers are also deleted automatically.
+
+73
+00:05:40,000 --> 00:05:49,000
+The trigger is invoked either before or after the following event insert when a euro is inserted hamdard
+
+74
+00:05:49,000 --> 00:05:51,000
+when an existing row is updated.
+
+75
+00:05:51,000 --> 00:05:54,000
+Delete when the row is deleted.
+
+76
+00:05:54,000 --> 00:05:58,000
+When you submit for execution and insert, update or delete statement.
+
+77
+00:05:59,000 --> 00:06:05,000
+Zero Relational Database Management System FAS as a corresponding trigger, always remember is that
+
+78
+00:06:05,000 --> 00:06:11,000
+it can be two triggers with similar action time and event for one table.
+
+79
+00:06:12,000 --> 00:06:20,000
+For example, we can't have two before update triggers for a table, but we can have before update and
+
+80
+00:06:20,000 --> 00:06:28,000
+before insert trigger or before and after they trigger, let's review the structure of the Create Trigger
+
+81
+00:06:28,000 --> 00:06:34,000
+statement we write Great trigger first trigger name should be unique.
+
+82
+00:06:34,000 --> 00:06:40,000
+After that, we specify, was a trigger should be activated before or after some event occurs.
+
+83
+00:06:41,000 --> 00:06:45,000
+Then we need to specify on which event we want to activate.
+
+84
+00:06:45,000 --> 00:06:51,000
+Our instructions is insert the date or the lead in which table.
+
+85
+00:06:51,000 --> 00:06:54,000
+After that, we can specify for each role.
+
+86
+00:06:55,000 --> 00:06:57,000
+This specifies a role level trigger.
+
+87
+00:06:58,000 --> 00:07:02,000
+For example, the trigger will be executed for each role being affected.
+
+88
+00:07:03,000 --> 00:07:05,000
+We can add trigger order.
+
+89
+00:07:05,000 --> 00:07:12,000
+This option might be useful if we have chain of triggers and we need to control that order.
+
+90
+00:07:12,000 --> 00:07:19,000
+And after all this, we need to describe trigger body that is exactly a set of instructions that are
+
+91
+00:07:19,000 --> 00:07:20,000
+needed to be executed.
+
+92
+00:07:21,000 --> 00:07:22,000
+Is everything clear?
+
+93
+00:07:22,000 --> 00:07:27,000
+Let's look at our practical demo and create one trigger as an example.
+
+94
+00:07:28,000 --> 00:07:35,000
+We are going to come up with some imaginary business case, imagine before inserting new actors in user
+
+95
+00:07:35,000 --> 00:07:35,000
+table.
+
+96
+00:07:35,000 --> 00:07:42,000
+We want to check that in case there is no well specified for foreign key F-k user role, fields should
+
+97
+00:07:42,000 --> 00:07:44,000
+be populated in this valley.
+
+98
+00:07:44,000 --> 00:07:44,000
+Six.
+
+99
+00:07:45,000 --> 00:07:49,000
+Yes, I know that for such purpose, we can set up default value for field.
+
+100
+00:07:50,000 --> 00:07:56,000
+But I want you to focus on the syntax right now, and I just want to present your syntax as simple as
+
+101
+00:07:56,000 --> 00:08:00,000
+possible without overcomplicate and business logic.
+
+102
+00:08:00,000 --> 00:08:08,000
+So attention to the syntax and my comments as we go, there is one more syntax specifics.
+
+103
+00:08:09,000 --> 00:08:13,000
+You can see that I specified another the name of the double ampersand.
+
+104
+00:08:14,000 --> 00:08:22,000
+Usually, we use a semicolon to separate those statements when writing SQL statements and MySQL client
+
+105
+00:08:22,000 --> 00:08:29,000
+program such as My SQL Revenge uses limited to separate statements and execute each statement separately.
+
+106
+00:08:30,000 --> 00:08:38,000
+However, for example, a stored procedure or trigger consists of multiple statements separated by semicolon,
+
+107
+00:08:38,000 --> 00:08:45,000
+and it will use my SQL workbench to define a trigger like in this case that contains semicolon characters.
+
+108
+00:08:46,000 --> 00:08:52,000
+The most equal client program will not treat the whole stored procedure, create statement or the whole
+
+109
+00:08:52,000 --> 00:08:58,000
+trigger create statement as a single statement, but many statements.
+
+110
+00:08:59,000 --> 00:09:05,000
+Therefore, we must really finds that the limiter temporarily so that we can pause the whole trigger
+
+111
+00:09:05,000 --> 00:09:08,000
+description to the server as a single statement.
+
+112
+00:09:09,000 --> 00:09:13,000
+That's why I said You didn't DeMatha at the beginning of this statement.
+
+113
+00:09:13,000 --> 00:09:17,000
+Andrew Chan it back to default at the end of the statement.
+
+114
+00:09:18,000 --> 00:09:23,000
+Execute multiple statements which can place trigger body between Begin and and keywords.
+
+115
+00:09:24,000 --> 00:09:28,000
+Basically, you can put here I'm a date insert delete statements.
+
+116
+00:09:28,000 --> 00:09:32,000
+You can address those statements to any table you wish.
+
+117
+00:09:32,000 --> 00:09:41,000
+And also, you can make conditions like I do here, I write, if followed by a predicate, some expressions,
+
+118
+00:09:41,000 --> 00:09:43,000
+a three chance is a true or false.
+
+119
+00:09:43,000 --> 00:09:49,000
+In this particular case, before inserting new value, I verifies its new value as it is going to be
+
+120
+00:09:49,000 --> 00:09:53,000
+inserted is not within the trigger body.
+
+121
+00:09:53,000 --> 00:09:56,000
+We can refer to columns in the subject table.
+
+122
+00:09:57,000 --> 00:10:02,000
+That is the table associated with the trigger by using the aliases.
+
+123
+00:10:02,000 --> 00:10:11,000
+Old and new art and column name refers to column often exists in the road before it is updated or deleted.
+
+124
+00:10:12,000 --> 00:10:19,000
+You and column the very first is a column often, you know, to be inserted or an existing row after
+
+125
+00:10:19,000 --> 00:10:20,000
+it is updated.
+
+126
+00:10:20,000 --> 00:10:21,000
+Does it make sense?
+
+127
+00:10:22,000 --> 00:10:28,000
+In the East Block, we can write any statements we wish, considering that we override the limit, that
+
+128
+00:10:28,000 --> 00:10:35,000
+we can use semicolon here to separate statements between each other at the end of the statement, I
+
+129
+00:10:35,000 --> 00:10:37,000
+should specify and if?
+
+130
+00:10:38,000 --> 00:10:44,000
+Once I declared all statements and about it, I should close triggered by what it was and the keyword.
+
+131
+00:10:45,000 --> 00:10:49,000
+And as we already discussed, I want to return the limits back to the fold.
+
+132
+00:10:50,000 --> 00:10:51,000
+Let's execute the statement.
+
+133
+00:10:52,000 --> 00:10:58,000
+And I see that query has been executed successfully and trigger is created.
+
+134
+00:10:59,000 --> 00:11:04,000
+You can check all existing triggers and this is where my SQL workbench do mouse.
+
+135
+00:11:04,000 --> 00:11:08,000
+Right click on the table and select out a table.
+
+136
+00:11:09,000 --> 00:11:14,000
+And on the three year tab, you can find all existing triggers to delete trigger.
+
+137
+00:11:14,000 --> 00:11:18,000
+You can click Mouse, right click and select Delete Trigger.
+
+138
+00:11:19,000 --> 00:11:25,000
+You can move the order of triggers here if you have multiple triggers, duplicate triggers, if needed,
+
+139
+00:11:25,000 --> 00:11:25,000
+and so on.
+
+140
+00:11:26,000 --> 00:11:28,000
+Let's see how trigger works.
+
+141
+00:11:29,000 --> 00:11:34,000
+So I add new records and deliberately leaving F-k user role at any time.
+
+142
+00:11:35,000 --> 00:11:43,000
+Let me apply changes and after changes applied, you can see that six has been added by default.
+
+143
+00:11:43,000 --> 00:11:51,000
+So before insertion, my triggers set the value to zero records is that I was about to act and only
+
+144
+00:11:51,000 --> 00:11:56,000
+after that insertion happened and I received a result like this.
+
+145
+00:11:57,000 --> 00:12:03,000
+In conclusion of triggers discussion, it is worth to mention some drawbacks of using triggers.
+
+146
+00:12:04,000 --> 00:12:08,000
+The main problem with triggers are they are completely global.
+
+147
+00:12:08,000 --> 00:12:16,000
+If you create a trigger to react on insertion event, that means that this rule will be applied to any
+
+148
+00:12:16,000 --> 00:12:19,000
+kind of insertion event without possibility.
+
+149
+00:12:19,000 --> 00:12:24,000
+Make an exclusion, at least sometimes logic on that the base layer.
+
+150
+00:12:24,000 --> 00:12:32,000
+Remember that creating triggers on the database layer you want your logic, the specific database and
+
+151
+00:12:32,000 --> 00:12:36,000
+then some degree detach your business logic from your app.
+
+152
+00:12:37,000 --> 00:12:44,000
+While triggers not always contain business rules and may be important piece in supporting of data consistency
+
+153
+00:12:44,000 --> 00:12:44,000
+database.
+
+154
+00:12:45,000 --> 00:12:51,000
+This is not always the case, and in case you make decisions, migrate to another database management
+
+155
+00:12:51,000 --> 00:12:52,000
+system.
+
+156
+00:12:52,000 --> 00:12:56,000
+It may become a pain to not lose any important operation.
+
+157
+00:12:56,000 --> 00:12:59,000
+Already scrapped and triggers triggers.
+
+158
+00:12:59,000 --> 00:13:02,000
+I still see by saying this.
+
+159
+00:13:02,000 --> 00:13:09,000
+I mean that it is easy to forget that there until they hurt you with unintended and very mysterious
+
+160
+00:13:09,000 --> 00:13:10,000
+consequences.
+
+161
+00:13:11,000 --> 00:13:14,000
+All this doesn't mean that you should never use triggers.
+
+162
+00:13:14,000 --> 00:13:21,000
+You just need to be aware of about this potential impact and use triggers carefully and wisely.
+
+163
+00:13:22,000 --> 00:13:25,000
+If everything is clear, let's move on.
+
+164
+00:13:26,000 --> 00:13:28,000
+Now, let's talk about stored procedures.
+
+165
+00:13:29,000 --> 00:13:32,000
+Let's learn what are they and how to work with them.
+
+166
+00:13:33,000 --> 00:13:37,000
+The start of procedure is a prepared sequel code is that you can see.
+
+167
+00:13:37,000 --> 00:13:40,000
+So the court can be reused over and over again.
+
+168
+00:13:41,000 --> 00:13:49,000
+So if you have an equal query that you write over and over again, save it as a stored procedure and
+
+169
+00:13:49,000 --> 00:13:51,000
+then just call it to execute it.
+
+170
+00:13:52,000 --> 00:13:59,000
+You can also put parameters to this procedure so that the procedure can act based on the parameter values
+
+171
+00:13:59,000 --> 00:14:00,000
+is at a sparse.
+
+172
+00:14:01,000 --> 00:14:05,000
+So what advantages of storage procedures performance?
+
+173
+00:14:06,000 --> 00:14:13,000
+The SQL server stored procedure when executed for the first time, creates a plan and stores it in the
+
+174
+00:14:13,000 --> 00:14:18,000
+buffer pool so that plan can be reused when it executes next time.
+
+175
+00:14:19,000 --> 00:14:25,000
+Reusable storage procedures can be executed by multiple users or multiple client applications without
+
+176
+00:14:25,000 --> 00:14:27,000
+the need of writing the code again.
+
+177
+00:14:28,000 --> 00:14:30,000
+It can be easily modified.
+
+178
+00:14:30,000 --> 00:14:37,000
+We can easily modify the code inside the stored procedure without the need to restart or deploying the
+
+179
+00:14:37,000 --> 00:14:39,000
+application security.
+
+180
+00:14:40,000 --> 00:14:45,000
+Stored procedures reduce this threat by eliminating direct access to the tables.
+
+181
+00:14:46,000 --> 00:14:53,000
+We can also encrypt the storage procedures while creating them so that source code and signs are stored.
+
+182
+00:14:53,000 --> 00:14:54,000
+Procedures not visible.
+
+183
+00:14:55,000 --> 00:14:57,000
+Reduced network traffic.
+
+184
+00:14:58,000 --> 00:15:04,000
+One When we use stored procedures instead of writing SQL queries as the application level only has a
+
+185
+00:15:04,000 --> 00:15:08,000
+procedure, name is passed over the network instead of the whole cycle code.
+
+186
+00:15:09,000 --> 00:15:13,000
+In of procedures, we can pass in and out parameters.
+
+187
+00:15:14,000 --> 00:15:18,000
+There are three types of parameters that we can pass and start procedures.
+
+188
+00:15:18,000 --> 00:15:27,000
+They are in, out and in, out in is an input only parameters which provide values to the storage procedure.
+
+189
+00:15:28,000 --> 00:15:31,000
+In addition, the value of in parameter is protected.
+
+190
+00:15:32,000 --> 00:15:39,000
+It means that even if you change the value of the parameter inside the stored procedure, its original
+
+191
+00:15:39,000 --> 00:15:43,000
+value is unchanged after the procedure ends.
+
+192
+00:15:44,000 --> 00:15:52,000
+In other words, the third procedure only works on the copy of in parameter and in parameter processing
+
+193
+00:15:52,000 --> 00:15:52,000
+value.
+
+194
+00:15:52,000 --> 00:15:59,000
+In the procedure, the procedure might modify the value, but the modification is not visible to the
+
+195
+00:15:59,000 --> 00:16:02,000
+caller when the procedure returns.
+
+196
+00:16:03,000 --> 00:16:10,000
+Out is output only parameters, which return values from this procedure, there's a Call-In program,
+
+197
+00:16:11,000 --> 00:16:18,000
+the value of an out parameter can be changed inside the stored procedure, and its new value is passed
+
+198
+00:16:18,000 --> 00:16:25,000
+back to IT program an out parameter processing value from the procedure back to the collar.
+
+199
+00:16:25,000 --> 00:16:31,000
+Its initial value is not within the procedure and its value is usable to the collar.
+
+200
+00:16:31,000 --> 00:16:34,000
+Was the procedure a chance you now?
+
+201
+00:16:34,000 --> 00:16:42,000
+It is an input and output parameters which provides values to and returns values from the stored procedure.
+
+202
+00:16:43,000 --> 00:16:46,000
+This is a combination of in and out parameters.
+
+203
+00:16:46,000 --> 00:16:53,000
+It means that the Coghlin program may cost the argument, and the stored procedure can modify the invalid
+
+204
+00:16:53,000 --> 00:17:00,000
+parameter and pass the new value back to the Collins program and out parameter is initialized by the
+
+205
+00:17:00,000 --> 00:17:07,000
+collar can be modified by the procedure, and any change made by the procedure is visible to the caller.
+
+206
+00:17:08,000 --> 00:17:16,000
+Once the procedure returns for each out or in that parameter, boss a user defined variable in the call
+
+207
+00:17:16,000 --> 00:17:23,000
+statement that involves the procedure so that you can obtain its value once the procedure returns.
+
+208
+00:17:23,000 --> 00:17:30,000
+If you are calling the procedure from within and not the stored procedure function, you can also pass
+
+209
+00:17:30,000 --> 00:17:35,000
+a routine parameter or local routine variable as an out or an out parameter.
+
+210
+00:17:36,000 --> 00:17:42,000
+If you are calling the procedure from within a trigger, you can also pass new column name as an out
+
+211
+00:17:42,000 --> 00:17:44,000
+or in that parameter.
+
+212
+00:17:44,000 --> 00:17:50,000
+The parameter leased and close was in parentheses must always be present.
+
+213
+00:17:50,000 --> 00:17:57,000
+If there are no parameters and empty parameters, at least should be used, parameter names are not
+
+214
+00:17:57,000 --> 00:17:58,000
+case sensitive.
+
+215
+00:17:59,000 --> 00:18:04,000
+Each parameter is an in parameter by default to specify otherwise for a parameter.
+
+216
+00:18:04,000 --> 00:18:08,000
+Use the keywords out or in out before the parameter name.
+
+217
+00:18:09,000 --> 00:18:15,000
+Don't worry if you are not feeling confident about understanding of different parameter types, we are
+
+218
+00:18:15,000 --> 00:18:21,000
+going to have them soon and it will be easier to understand was examples if you understood the theory
+
+219
+00:18:21,000 --> 00:18:24,000
+of stored procedures and why we need them.
+
+220
+00:18:24,000 --> 00:18:26,000
+Let's hold a demo.
+
+221
+00:18:27,000 --> 00:18:29,000
+Let's create a simple procedure.
+
+222
+00:18:29,000 --> 00:18:32,000
+Our procedure will select the user by email.
+
+223
+00:18:32,000 --> 00:18:36,000
+You already know why I set different animals are in my school query.
+
+224
+00:18:37,000 --> 00:18:40,000
+The reason is the same as an example with triggers.
+
+225
+00:18:41,000 --> 00:18:43,000
+Here's an example was in parameter.
+
+226
+00:18:44,000 --> 00:18:51,000
+Important thing to remember Bear tensions at the name of the parameter and name of column in where clause
+
+227
+00:18:51,000 --> 00:18:52,000
+should be different.
+
+228
+00:18:52,000 --> 00:18:59,000
+You know, the server would understand where you referred the parameter and where you refer to the column.
+
+229
+00:19:00,000 --> 00:19:06,000
+After that, I right begin keywords and after that go start procedure body.
+
+230
+00:19:06,000 --> 00:19:08,000
+Well, we can specify our instructions.
+
+231
+00:19:09,000 --> 00:19:11,000
+One procedure body is finished.
+
+232
+00:19:11,000 --> 00:19:13,000
+We use and keywords.
+
+233
+00:19:16,000 --> 00:19:24,000
+Now we can easily execute this stored procedure with the help of coal keywords and possibly the email
+
+234
+00:19:24,000 --> 00:19:28,000
+parameter in case we wouldn't pass email parameter.
+
+235
+00:19:28,000 --> 00:19:33,000
+We would see error that would tell us about wrong number of parameters.
+
+236
+00:19:34,000 --> 00:19:38,000
+And here is record with the correct email has been returned.
+
+237
+00:19:38,000 --> 00:19:41,000
+Do understand how to create stored procedure and how to call it.
+
+238
+00:19:42,000 --> 00:19:48,000
+As you can see, there is nothing complex in this, but probably a few questions still in the eye at
+
+239
+00:19:48,000 --> 00:19:51,000
+how the work was out and in parameters.
+
+240
+00:19:51,000 --> 00:19:52,000
+Correct.
+
+241
+00:19:53,000 --> 00:19:53,000
+As I promised you.
+
+242
+00:19:54,000 --> 00:19:57,000
+Let me show a practical example with these types of parameters.
+
+243
+00:19:58,000 --> 00:20:04,000
+Let's create procedure now that will return us average amount of money in our parameter.
+
+244
+00:20:04,000 --> 00:20:08,000
+As you can see, I vividly specifies that this is out parameter.
+
+245
+00:20:09,000 --> 00:20:17,000
+And after that inside procedure, I use into key words to stores the result into the out parameter.
+
+246
+00:20:18,000 --> 00:20:18,000
+Is that clear?
+
+247
+00:20:19,000 --> 00:20:21,000
+You should be familiar with this query.
+
+248
+00:20:22,000 --> 00:20:25,000
+This is aggregate functions that you reviewed in a separate lesson.
+
+249
+00:20:26,000 --> 00:20:32,000
+So in case you want to learn more about average and aggregate functions, feel free to review previous
+
+250
+00:20:32,000 --> 00:20:36,000
+lessons in the same way we create this stored procedure.
+
+251
+00:20:37,000 --> 00:20:43,000
+And now let's learn what is different during the invocation of this stored procedure when we call our
+
+252
+00:20:43,000 --> 00:20:44,000
+stored procedure.
+
+253
+00:20:45,000 --> 00:20:53,000
+We pass so-called session variable as a parameter to receive returns value because we need that reference
+
+254
+00:20:53,000 --> 00:20:56,000
+to the variable to retrieve a result of a storage procedure.
+
+255
+00:20:56,000 --> 00:21:04,000
+Execution A session variable is a user defined variables that starts was at sine doesn't require declaration
+
+256
+00:21:05,000 --> 00:21:12,000
+can be used in any SQL query or statement non-visible to other sessions and exists until the end of
+
+257
+00:21:12,000 --> 00:21:13,000
+the current session.
+
+258
+00:21:14,000 --> 00:21:19,000
+And after that, we can refer to this variable to get the value that was recorded into it.
+
+259
+00:21:20,000 --> 00:21:23,000
+I use simple select statement Does it make sense?
+
+260
+00:21:24,000 --> 00:21:26,000
+Is it not clear now home?
+
+261
+00:21:26,000 --> 00:21:27,000
+That was this example.
+
+262
+00:21:27,000 --> 00:21:30,000
+It is not clear how to use our parameter.
+
+263
+00:21:31,000 --> 00:21:34,000
+It looks like I have one more parameter type to show.
+
+264
+00:21:35,000 --> 00:21:37,000
+Let me show you example of in-out parameter.
+
+265
+00:21:38,000 --> 00:21:42,000
+In this example, we are going to implement counter stored procedure.
+
+266
+00:21:43,000 --> 00:21:49,000
+This procedure will take input parameter, will increase it by the specified amount and will return
+
+267
+00:21:49,000 --> 00:21:54,000
+as a value in the body of our stored procedure will incremento account.
+
+268
+00:21:55,000 --> 00:21:56,000
+That's it.
+
+269
+00:21:57,000 --> 00:22:04,000
+Let's look how we work with this kind of stored procedures and declare a session variable and initialize
+
+270
+00:22:04,000 --> 00:22:05,000
+it with some value.
+
+271
+00:22:06,000 --> 00:22:12,000
+After that, I call my stored procedure a few times by passing the same session variable and incremental
+
+272
+00:22:12,000 --> 00:22:12,000
+value.
+
+273
+00:22:13,000 --> 00:22:18,000
+After all this, I can read my session variable to find that it was incremented.
+
+274
+00:22:19,000 --> 00:22:25,000
+That proves that the state of our counter session variable was modified multiple times is every single
+
+275
+00:22:25,000 --> 00:22:26,000
+year.
+
+276
+00:22:26,000 --> 00:22:33,000
+And by the way, I have never shown you before how to request comments in my school robberies is just
+
+277
+00:22:33,000 --> 00:22:38,000
+below neat in this the different types of comments that you can use in my school.
+
+278
+00:22:39,000 --> 00:22:42,000
+First kind of comments that you can see here is double dash.
+
+279
+00:22:42,000 --> 00:22:45,000
+The comments must be at the end of a line.
+
+280
+00:22:45,000 --> 00:22:49,000
+Your SQL statement was a line break off the list.
+
+281
+00:22:49,000 --> 00:22:56,000
+Mazeltov comment and can only span a single line was in your school statement and must be at the end
+
+282
+00:22:56,000 --> 00:22:57,000
+of the line.
+
+283
+00:22:58,000 --> 00:23:01,000
+Another type of comment is similar to the previous one.
+
+284
+00:23:01,000 --> 00:23:06,000
+Just one more syntax of a single line comment started with a no sign.
+
+285
+00:23:07,000 --> 00:23:10,000
+Also, you can use Mutula in common in multi-line comment.
+
+286
+00:23:10,000 --> 00:23:14,000
+You should specify where a comment is started and where it is finished.
+
+287
+00:23:15,000 --> 00:23:22,000
+I'm not showing you how to alter and drop stored procedures because it is similar to dropping and altering
+
+288
+00:23:22,000 --> 00:23:24,000
+other database objects.
+
+289
+00:23:24,000 --> 00:23:28,000
+Just click mouse rightly constraint procedure that you are interested in.
+
+290
+00:23:29,000 --> 00:23:32,000
+Well, that it's regarding this example.
+
+291
+00:23:33,000 --> 00:23:38,000
+And now let's talk about functions and understand how they're different from stored procedures.
+
+292
+00:23:39,000 --> 00:23:45,000
+A function in my school is a program that is used to perform an action such as complex calculations,
+
+293
+00:23:46,000 --> 00:23:49,000
+for example, and returns the result of an action as a value.
+
+294
+00:23:50,000 --> 00:23:52,000
+Does it look like something similar to you?
+
+295
+00:23:53,000 --> 00:23:55,000
+Something what we have just discussed.
+
+296
+00:23:56,000 --> 00:24:01,000
+You are not the only one who wants to understand the difference between stored procedure and functions
+
+297
+00:24:01,000 --> 00:24:01,000
+and sequel.
+
+298
+00:24:02,000 --> 00:24:06,000
+Wait for a minute, and I will explain in detail what exactly the difference is.
+
+299
+00:24:07,000 --> 00:24:10,000
+There are two types of functions available in my sequel.
+
+300
+00:24:11,000 --> 00:24:15,000
+They are system defined functions and user defined functions.
+
+301
+00:24:16,000 --> 00:24:22,000
+We'll discuss system defined functions and a separate lesson, the function, which is defined by a
+
+302
+00:24:22,000 --> 00:24:25,000
+user, is called a user defined function.
+
+303
+00:24:26,000 --> 00:24:33,000
+My skill user defined functions may or may not have parameters at the optional, but it always returns
+
+304
+00:24:33,000 --> 00:24:35,000
+a single value that is mandatory.
+
+305
+00:24:36,000 --> 00:24:42,000
+The returned value which is returned by then my single function can be often an invalid.
+
+306
+00:24:42,000 --> 00:24:45,000
+My SQL data type regarding parameters and function.
+
+307
+00:24:46,000 --> 00:24:48,000
+Hammerson is much single isn't stored procedures.
+
+308
+00:24:49,000 --> 00:24:56,000
+You don't have different types of parameters like E out or announce all parameters and functions registered
+
+309
+00:24:56,000 --> 00:24:57,000
+as any parameters.
+
+310
+00:24:58,000 --> 00:25:02,000
+Now let's review high level syntax of great function statement.
+
+311
+00:25:02,000 --> 00:25:07,000
+First of all, specifies the name of the search function that you want to create after create function
+
+312
+00:25:07,000 --> 00:25:08,000
+keywords.
+
+313
+00:25:09,000 --> 00:25:15,000
+Secondly, list all parameters of the storage function inside the parentheses, followed by the function
+
+314
+00:25:15,000 --> 00:25:15,000
+name.
+
+315
+00:25:16,000 --> 00:25:21,000
+And as we have discussed by default, all parameters are the end parameters.
+
+316
+00:25:21,000 --> 00:25:30,000
+We can't specify in, out or in that modifies the parameters such centered specifies the data type of
+
+317
+00:25:30,000 --> 00:25:35,000
+the return value in the returns statement, which can be an invalid my school data type.
+
+318
+00:25:36,000 --> 00:25:44,000
+Force specify if a function is deterministic or not, using such deterministic keyword and deterministic
+
+319
+00:25:44,000 --> 00:25:50,000
+function always returns the same result for the same input parameters, whereas a non deterministic
+
+320
+00:25:50,000 --> 00:25:54,000
+function returns different results for the same input parameters.
+
+321
+00:25:55,000 --> 00:26:02,000
+If you don't use deterministic or not deterministic, my cycle uses are not deterministic option by
+
+322
+00:26:02,000 --> 00:26:10,000
+default, fifths rides are caught in the body of the storage function in the begin and block inside
+
+323
+00:26:10,000 --> 00:26:10,000
+them.
+
+324
+00:26:10,000 --> 00:26:11,000
+What is section?
+
+325
+00:26:11,000 --> 00:26:14,000
+You need to specify at least one return statement.
+
+326
+00:26:14,000 --> 00:26:20,000
+Zero chance statements returns a value to the call and programs when there was a written statement is
+
+327
+00:26:20,000 --> 00:26:21,000
+reached.
+
+328
+00:26:21,000 --> 00:26:25,000
+Six Kusum of the storage function is terminated immediately.
+
+329
+00:26:26,000 --> 00:26:31,000
+Let's look at the demo of functions now and after that will somes a difference.
+
+330
+00:26:31,000 --> 00:26:31,000
+A step.
+
+331
+00:26:32,000 --> 00:26:38,000
+And now example, let's create a function that can identify user status based on the amount of money
+
+332
+00:26:38,000 --> 00:26:40,000
+he or she has.
+
+333
+00:26:40,000 --> 00:26:43,000
+The function will take money as method argument.
+
+334
+00:26:43,000 --> 00:26:46,000
+It will return the value of virtual data type.
+
+335
+00:26:47,000 --> 00:26:49,000
+This is deterministic function.
+
+336
+00:26:50,000 --> 00:26:56,000
+We declare a variable and dependent on the amount of money we initialize this variable with one or another
+
+337
+00:26:56,000 --> 00:26:56,000
+value.
+
+338
+00:26:57,000 --> 00:27:04,000
+And at the end of the function body, when returns of value is ever seen clear here, please press a
+
+339
+00:27:04,000 --> 00:27:07,000
+pause if you want to look at all lines more thoroughly.
+
+340
+00:27:08,000 --> 00:27:12,000
+We executed this SQL statement and we have a function created.
+
+341
+00:27:13,000 --> 00:27:20,000
+You can easily list and review all functions that exist in the database, like this show function status
+
+342
+00:27:21,000 --> 00:27:22,000
+and specifies the database.
+
+343
+00:27:23,000 --> 00:27:27,000
+We can see that in our database, only one function is declared so far.
+
+344
+00:27:28,000 --> 00:27:29,000
+Let's invoke it now.
+
+345
+00:27:30,000 --> 00:27:36,000
+And you can already find one more difference between search function and storage procedure different
+
+346
+00:27:36,000 --> 00:27:43,000
+from a stored procedure, you can use a stored function in SQL statements wherever an expression is
+
+347
+00:27:43,000 --> 00:27:44,000
+used.
+
+348
+00:27:44,000 --> 00:27:49,000
+This helps improve the readability and mental ability of the procedural code.
+
+349
+00:27:50,000 --> 00:27:57,000
+In our example, I want to extract last name of user management and get the result of my function for
+
+350
+00:27:57,000 --> 00:27:57,000
+each record.
+
+351
+00:27:58,000 --> 00:28:02,000
+You can see that I invoke function here and post-money value to it.
+
+352
+00:28:03,000 --> 00:28:04,000
+Let's see what we'll get.
+
+353
+00:28:05,000 --> 00:28:09,000
+And you can see that as a result, we get what we expected.
+
+354
+00:28:09,000 --> 00:28:15,000
+Function has been applied to each record and returns us correct status for each user.
+
+355
+00:28:15,000 --> 00:28:16,000
+Then the stent.
+
+356
+00:28:16,000 --> 00:28:19,000
+Now how to create and execute function.
+
+357
+00:28:19,000 --> 00:28:21,000
+If yes, Zenith is great.
+
+358
+00:28:22,000 --> 00:28:28,000
+Now, when you saw functions and stored procedures, let's summarize what the difference is between
+
+359
+00:28:28,000 --> 00:28:28,000
+them.
+
+360
+00:28:29,000 --> 00:28:33,000
+There are numerous differences between storage procedures and storage functions.
+
+361
+00:28:34,000 --> 00:28:34,000
+That's true.
+
+362
+00:28:34,000 --> 00:28:41,000
+Using important ones, the function must return the value, but in standard procedure, it is optional
+
+363
+00:28:41,000 --> 00:28:42,000
+in the procedure.
+
+364
+00:28:42,000 --> 00:28:48,000
+We can return zero or and various functions can have on the input parameters for it.
+
+365
+00:28:49,000 --> 00:28:52,000
+Various procedures can have input or output parameters.
+
+366
+00:28:53,000 --> 00:29:00,000
+Functions can be called from procedure, whereas procedures cannot be called from a function.
+
+367
+00:29:01,000 --> 00:29:09,000
+The procedure allows select as well as insert update delete statements in it, whereas function allows
+
+368
+00:29:09,000 --> 00:29:10,000
+only a select statement in it.
+
+369
+00:29:11,000 --> 00:29:19,000
+Procedures can be utilized in a select statement, whereas function can be embedded in that select statement.
+
+370
+00:29:19,000 --> 00:29:27,000
+Stored procedures can't be used in the sequel statements anywhere in the where having select section
+
+371
+00:29:28,000 --> 00:29:35,000
+various function can be an exception can be handled by try catch block in the procedure, whereas try
+
+372
+00:29:35,000 --> 00:29:38,000
+catch block can't be used in a function.
+
+373
+00:29:39,000 --> 00:29:45,000
+We can use transactions in procedure, whereas we can't use transactions in function.
+
+374
+00:29:46,000 --> 00:29:49,000
+I believe that we captured and review of the main differences.
+
+375
+00:29:50,000 --> 00:29:52,000
+That's all for this lesson.
+
+376
+00:29:52,000 --> 00:29:56,000
+Let's recap what we have learned in the video today.
+
+377
+00:29:56,000 --> 00:29:58,000
+We have learned what views are.
+
+378
+00:29:58,000 --> 00:30:02,000
+We created our custom views and based on our existing tables.
+
+379
+00:30:02,000 --> 00:30:08,000
+I explained to you what triggers are now you know, how to create and work with stored procedures.
+
+380
+00:30:09,000 --> 00:30:16,000
+As we reviewed the examples, we learned different types of comments in Sequel Dilemma during my SQL
+
+381
+00:30:16,000 --> 00:30:17,000
+and session variables.
+
+382
+00:30:18,000 --> 00:30:25,000
+At the end of the lesson, we have learned functions and we learnt differences between functions and
+
+383
+00:30:25,000 --> 00:30:26,000
+stored procedures.
+
+384
+00:30:26,000 --> 00:30:28,000
+That's all for today.
+
+385
+00:30:28,000 --> 00:30:30,000
+Thanks a lot for your attention.
+
+386
+00:30:30,000 --> 00:30:31,000
+Have a great day.
+
+387
+00:30:31,000 --> 00:30:33,000
+See you in the next lesson.
+

49 - Relational Databases (Advanced)/002 MySQL Workbench Administration_en.srt

@@ -0,0 +1,508 @@
+1
+00:00:06,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:06,000 --> 00:00:09,000
+In this lesson, we're going to learn database administration.
+
+3
+00:00:10,000 --> 00:00:15,000
+We're going to learn how to configure users random necessary rights to perform actions and database
+
+4
+00:00:16,000 --> 00:00:21,000
+how to track database performance, manage data expert and data inputs.
+
+5
+00:00:21,000 --> 00:00:27,000
+Definitely, this lesson is going to be interesting and useful for you in this lesson.
+
+6
+00:00:27,000 --> 00:00:32,000
+I'm going to do a lot of screen sharing on the example of my school workbench.
+
+7
+00:00:32,000 --> 00:00:39,000
+I'm going to show you how easily you can perform such basic operations as data import expert, new user
+
+8
+00:00:39,000 --> 00:00:46,000
+creation, configuring the and access for new account and track, or my SQL server performance.
+
+9
+00:00:46,000 --> 00:00:47,000
+Let's stop.
+
+10
+00:00:47,000 --> 00:00:53,000
+And as I already said today, we're going to have a lot of them examples on screen sharing.
+
+11
+00:00:53,000 --> 00:00:55,000
+So let me start sharing my screen.
+
+12
+00:00:56,000 --> 00:00:59,000
+Let's start from learning data expert and data input.
+
+13
+00:01:00,000 --> 00:01:06,000
+First of all, I want to show you a few menus and apps in my school workbench here, where for administration
+
+14
+00:01:06,000 --> 00:01:12,000
+tap and under management section, you can find data experts and data options.
+
+15
+00:01:13,000 --> 00:01:18,000
+Also, you can click on several menu to find data expert and data in-person options.
+
+16
+00:01:18,000 --> 00:01:19,000
+Why we need this.
+
+17
+00:01:20,000 --> 00:01:26,000
+For example, you need to configure a local database and populated with necessary data from production
+
+18
+00:01:26,000 --> 00:01:27,000
+environments.
+
+19
+00:01:28,000 --> 00:01:31,000
+These are for local development, debugging or any other purpose.
+
+20
+00:01:32,000 --> 00:01:40,000
+You do data experts in one place and do data in court in your local database, or imagine that you developed
+
+21
+00:01:40,000 --> 00:01:43,000
+your app and create a database structure.
+
+22
+00:01:43,000 --> 00:01:47,000
+And now it is time to go live and move to a production environment.
+
+23
+00:01:48,000 --> 00:01:54,000
+And as an example, let's imagine that we need to do experts of our learning database and all datasets
+
+24
+00:01:54,000 --> 00:01:56,000
+we created during the previous lessons.
+
+25
+00:01:57,000 --> 00:02:00,000
+Data expert I need to select database.
+
+26
+00:02:01,000 --> 00:02:04,000
+And when I select a database, I can select tables that I want to export.
+
+27
+00:02:05,000 --> 00:02:12,000
+Now, pay attention here if I want to initialize my database and production firm, and I don't need
+
+28
+00:02:12,000 --> 00:02:13,000
+test data at all.
+
+29
+00:02:14,000 --> 00:02:15,000
+I have few options here.
+
+30
+00:02:16,000 --> 00:02:22,000
+Namely, I can dump structure only if you need both data and structure.
+
+31
+00:02:23,000 --> 00:02:27,000
+You can select the option that will tell my school to dump data and structure.
+
+32
+00:02:28,000 --> 00:02:35,000
+Below, you can find check boxes that allow you to indicate whether you are ready to export stored procedures,
+
+33
+00:02:35,000 --> 00:02:37,000
+functions, triggers, events.
+
+34
+00:02:38,000 --> 00:02:44,000
+Below, you can find check boxes that allow you to indicate whether you want to export stored procedures.
+
+35
+00:02:44,000 --> 00:02:48,000
+Functions triggers events in exports options.
+
+36
+00:02:48,000 --> 00:02:54,000
+You can specify Project Folder for the dump in case you would specify Project Folder.
+
+37
+00:02:54,000 --> 00:03:01,000
+Each table will be exported as a separate file in case you select export self-contained file.
+
+38
+00:03:01,000 --> 00:03:05,000
+All instructions will be export that single file.
+
+39
+00:03:05,000 --> 00:03:09,000
+Pay attention that on my screen and probably on your stoop.
+
+40
+00:03:10,000 --> 00:03:13,000
+It is not possible to investigate all possible configurations.
+
+41
+00:03:14,000 --> 00:03:19,000
+Just resize widgets like I do here to see all menus and buttons.
+
+42
+00:03:20,000 --> 00:03:26,000
+You can enable creation of dump in a single transaction and include create schema to.
+
+43
+00:03:27,000 --> 00:03:34,000
+After you configure, it's everything you need, just click Start Export button after exports is finished.
+
+44
+00:03:34,000 --> 00:03:40,000
+You can find the results of your exports is a destination that has been configured as a result of the
+
+45
+00:03:40,000 --> 00:03:48,000
+export is nothing more than sequel instructions that create database abuse and insert waiting tables
+
+46
+00:03:48,000 --> 00:03:48,000
+if needed.
+
+47
+00:03:50,000 --> 00:03:53,000
+Now, let's import data into our database.
+
+48
+00:03:53,000 --> 00:04:01,000
+Select Data Import Specify is a project folder with your sequel queries or select radio bottom to specify
+
+49
+00:04:01,000 --> 00:04:02,000
+self-contained file.
+
+50
+00:04:03,000 --> 00:04:08,000
+You can select schema from where to import data or create a new one.
+
+51
+00:04:08,000 --> 00:04:15,000
+This is needed for cases if your sequel instructions that you are going to import don't contain, create
+
+52
+00:04:15,000 --> 00:04:16,000
+schema statement.
+
+53
+00:04:17,000 --> 00:04:20,000
+After that, just click Start Import button, and that's it.
+
+54
+00:04:21,000 --> 00:04:24,000
+They understand how to export and import data.
+
+55
+00:04:24,000 --> 00:04:31,000
+Now, let's now learn how to create users and grant them privileges in management section.
+
+56
+00:04:31,000 --> 00:04:33,000
+I click on user and privileges.
+
+57
+00:04:33,000 --> 00:04:36,000
+Sure, you can see list of user accounts.
+
+58
+00:04:36,000 --> 00:04:39,000
+As you can see, there are some accounts already created.
+
+59
+00:04:40,000 --> 00:04:41,000
+Let's learn What are they?
+
+60
+00:04:42,000 --> 00:04:50,000
+One part of the Mexico installation process is Data Directory initialization durin data directory initialization.
+
+61
+00:04:50,000 --> 00:04:58,000
+My SQL creates user accounts that should be considered to reserve my SQL info schema localhost used
+
+62
+00:04:58,000 --> 00:05:02,000
+as a definer for information schema of use use of them.
+
+63
+00:05:02,000 --> 00:05:09,000
+My SQL Info Schema account avoids problems that occur if a database administrator rename or removes
+
+64
+00:05:09,000 --> 00:05:10,000
+a root account.
+
+65
+00:05:11,000 --> 00:05:18,000
+Use of the My SQL Info Schema account avoids problems that occur if a database administrator names or
+
+66
+00:05:18,000 --> 00:05:20,000
+removes the root account.
+
+67
+00:05:20,000 --> 00:05:26,000
+This account is logged so that it can be used for client connections.
+
+68
+00:05:27,000 --> 00:05:33,000
+My school session localhost used internally by plug ins to access the server.
+
+69
+00:05:33,000 --> 00:05:38,000
+This account is locked so that it can't be used for client connections.
+
+70
+00:05:38,000 --> 00:05:43,000
+My sequels to Sparklehorse used as a defined the forces schema.
+
+71
+00:05:43,000 --> 00:05:46,000
+Objects use of them are sequels.
+
+72
+00:05:46,000 --> 00:05:52,000
+Sequences account avoids problems that occur if a DP renames or removes their account.
+
+73
+00:05:52,000 --> 00:05:57,000
+This account is locked so that it can't be used for client connections.
+
+74
+00:05:58,000 --> 00:06:06,000
+Root localhost used for administrative purposes, this account has old privileges and can perform any
+
+75
+00:06:06,000 --> 00:06:06,000
+operation.
+
+76
+00:06:07,000 --> 00:06:14,000
+Strictly speaking, this account's name is not reserved in the sense that some installations renamed
+
+77
+00:06:14,000 --> 00:06:20,000
+the root account or something else to avoid exposing a highly privileged account was a well known name.
+
+78
+00:06:21,000 --> 00:06:27,000
+But what to do in case we need to create a new user was a separate set of religious Zahra might be different
+
+79
+00:06:27,000 --> 00:06:28,000
+cases.
+
+80
+00:06:28,000 --> 00:06:33,000
+For example, unions separate account for development purposes and you need to restrict some rights
+
+81
+00:06:33,000 --> 00:06:38,000
+for it or you create a database account for your application.
+
+82
+00:06:38,000 --> 00:06:41,000
+And you deliberately want to keep only read rights.
+
+83
+00:06:41,000 --> 00:06:42,000
+Does it make sense?
+
+84
+00:06:43,000 --> 00:06:46,000
+The great new user click Add Account here.
+
+85
+00:06:46,000 --> 00:06:54,000
+We can change the name of new account, select our syndication type for the standard login password
+
+86
+00:06:54,000 --> 00:06:58,000
+densification select standard that's come up was the passwords.
+
+87
+00:06:59,000 --> 00:07:05,000
+You can even configure account limit, for example, amount of queries that can be executed per hour
+
+88
+00:07:06,000 --> 00:07:09,000
+max number of connections concurrent connections.
+
+89
+00:07:10,000 --> 00:07:14,000
+You can check this step to explore more administrative roles.
+
+90
+00:07:14,000 --> 00:07:17,000
+Tap, in my opinion, very important one.
+
+91
+00:07:17,000 --> 00:07:20,000
+You need to grant privileges to your account.
+
+92
+00:07:20,000 --> 00:07:27,000
+In other words, you'll need to specify what new account can and can't do in the database.
+
+93
+00:07:27,000 --> 00:07:33,000
+You can select one or more predefined rules, or you can select privileges manually.
+
+94
+00:07:34,000 --> 00:07:41,000
+It is only up to you and on the last stop here in skimmer privileges, you may said you are just related
+
+95
+00:07:41,000 --> 00:07:42,000
+to schemas.
+
+96
+00:07:42,000 --> 00:07:49,000
+You can add rules for all schemas schemas that margins are provided foreign and concrete schemas.
+
+97
+00:07:50,000 --> 00:07:55,000
+By the way, you can grant and revoke religious even after you create that user account.
+
+98
+00:07:57,000 --> 00:08:03,000
+After you configure it, everything, just click on the apply button and the user will be created.
+
+99
+00:08:03,000 --> 00:08:07,000
+So we created account with select privileges only.
+
+100
+00:08:08,000 --> 00:08:11,000
+Let's now establish new connection using our new credentials.
+
+101
+00:08:12,000 --> 00:08:14,000
+And let's try to drop some table.
+
+102
+00:08:33,000 --> 00:08:40,000
+And you can see that when I tried to drop a table, the command wasn't executed, command was denied
+
+103
+00:08:40,000 --> 00:08:41,000
+for my user.
+
+104
+00:08:42,000 --> 00:08:46,000
+But I still can select any information I need from this schema.
+
+105
+00:08:46,000 --> 00:08:47,000
+Is that clear?
+
+106
+00:08:48,000 --> 00:08:52,000
+Can we understand now how privileges work and how to configure them?
+
+107
+00:08:53,000 --> 00:08:59,000
+The last thing that I'd like quickly to show you is how to track performance of my SQL server in my
+
+108
+00:08:59,000 --> 00:09:00,000
+school workbench.
+
+109
+00:09:00,000 --> 00:09:03,000
+There is a separate section here, as it is called performance.
+
+110
+00:09:04,000 --> 00:09:07,000
+You can open dashboard and track performance in real time.
+
+111
+00:09:08,000 --> 00:09:14,000
+On the dashboards, you can find network status, my SQL status and energy status.
+
+112
+00:09:14,000 --> 00:09:21,000
+When you have queries executed, you will see that this charts will be defined and you can see some
+
+113
+00:09:21,000 --> 00:09:22,000
+measurements here.
+
+114
+00:09:23,000 --> 00:09:27,000
+There are separate widgets that allow you to track status of the storage engine.
+
+115
+00:09:28,000 --> 00:09:31,000
+Most of the metrics and widgets are self-described.
+
+116
+00:09:32,000 --> 00:09:36,000
+And if you follow this course, there is nothing new for you.
+
+117
+00:09:37,000 --> 00:09:43,000
+You should already know what in the day is, what SQL statements are, what select and search create
+
+118
+00:09:43,000 --> 00:09:45,000
+update alternate means.
+
+119
+00:09:46,000 --> 00:09:49,000
+That's all what I wanted to share with you in this lesson.
+
+120
+00:09:50,000 --> 00:09:52,000
+Let's recap what we have learned today.
+
+121
+00:09:53,000 --> 00:09:59,000
+In this lesson, we learned how to make data expert also use, for example, with data inputs.
+
+122
+00:10:00,000 --> 00:10:01,000
+We created new user with you.
+
+123
+00:10:02,000 --> 00:10:08,000
+We can figure global privileges POIs and also contributes schema privileges and advantages.
+
+124
+00:10:08,000 --> 00:10:11,000
+Larson I showed you performance dashboard in my sequel.
+
+125
+00:10:12,000 --> 00:10:12,000
+That's it.
+
+126
+00:10:13,000 --> 00:10:15,000
+Thank you all for your attention.
+
+127
+00:10:15,000 --> 00:10:18,000
+Have a great day and see you in the next lesson.
+

49 - Relational Databases (Advanced)/external-links.txt

@@ -0,0 +1,3 @@
+
+001 Find-folders-with-Views-Triggers-Stored-Procedures-and-Stored-Functions-SQL-query-examples-here
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/sql_queries/ddl

50 - Databases Database Modelling and Architecture/001 Database Modelling & Design Conceptual, Logical and Physical Data Models_en.srt

@@ -0,0 +1,1160 @@
+1
+00:00:05,000 --> 00:00:11,000
+Hello, Kim, in this lesson, we're going to review very important theoretical concepts of data modeling.
+
+2
+00:00:12,000 --> 00:00:17,000
+This lesson will be useful for everyone, no matter whether you architect or database engineer.
+
+3
+00:00:18,000 --> 00:00:24,000
+We need to learn and understand the basic concepts of data modeling on different levels and different
+
+4
+00:00:24,000 --> 00:00:25,000
+phases of our project.
+
+5
+00:00:26,000 --> 00:00:33,000
+The fundamental understanding of this process has helped me to save a lot of time and avoid a lot of
+
+6
+00:00:33,000 --> 00:00:35,000
+mistakes and rework in the past.
+
+7
+00:00:36,000 --> 00:00:39,000
+That's why I believe it is super important me sharing this with you.
+
+8
+00:00:40,000 --> 00:00:46,000
+We are going to learn such terms as data model, data context, database design, probably explaining
+
+9
+00:00:46,000 --> 00:00:49,000
+why data modeling is super important.
+
+10
+00:00:49,000 --> 00:00:55,000
+And I will provide you with tools and algorithms to ensure efficient process on your project.
+
+11
+00:00:55,000 --> 00:01:02,000
+And after that, we are going to dive into specifics of different data model types and use those with
+
+12
+00:01:02,000 --> 00:01:02,000
+examples.
+
+13
+00:01:03,000 --> 00:01:09,000
+Namely, we are going to discuss conceptual data model, logical data model and physical data model.
+
+14
+00:01:10,000 --> 00:01:15,000
+But then the last thing you are going to have a clear understanding about each type of data model and
+
+15
+00:01:15,000 --> 00:01:16,000
+differences between them.
+
+16
+00:01:17,000 --> 00:01:20,000
+Let's understand first what data model is.
+
+17
+00:01:20,000 --> 00:01:28,000
+A data model is an abstract model that organizes elements of data and standardize how they relate to
+
+18
+00:01:28,000 --> 00:01:32,000
+one another and to the properties of the real world with this.
+
+19
+00:01:33,000 --> 00:01:40,000
+For example, a data model may specify that the data elements representing a car be composed of a number
+
+20
+00:01:40,000 --> 00:01:49,000
+of elements, which in turn represent a color and the size of the car and define its own term data model
+
+21
+00:01:49,000 --> 00:01:54,000
+can refer to two distinct but closely related concepts.
+
+22
+00:01:54,000 --> 00:02:01,000
+Sometimes it refers to an absolute formalization of the objects and relationships found, in particular
+
+23
+00:02:01,000 --> 00:02:03,000
+application domain.
+
+24
+00:02:03,000 --> 00:02:11,000
+For example, the customers products and orders found in manufacturing and analyzation, and other times
+
+25
+00:02:11,000 --> 00:02:16,000
+it refers to a set of concepts used in defining such formalization.
+
+26
+00:02:17,000 --> 00:02:22,000
+For example, concepts such as entities, attributes, relations or tables.
+
+27
+00:02:23,000 --> 00:02:29,000
+So is a data model of a banking application may be defined using the entity.
+
+28
+00:02:29,000 --> 00:02:35,000
+Relationship data model and data model explicitly determines the structure of data.
+
+29
+00:02:36,000 --> 00:02:40,000
+The next item is related to the previous one database model.
+
+30
+00:02:41,000 --> 00:02:49,000
+What is a database model that the base model is a type of data model that determines zoological structure
+
+31
+00:02:49,000 --> 00:02:50,000
+of a database.
+
+32
+00:02:50,000 --> 00:02:57,000
+It fundamentally determines in which manner data can be stored, organized and manipulated.
+
+33
+00:02:57,000 --> 00:03:04,000
+The most popular example of database model is a relational model, which uses a table based format.
+
+34
+00:03:05,000 --> 00:03:12,000
+Database model refers to the logical structure, representation all the out of the database and how
+
+35
+00:03:12,000 --> 00:03:17,000
+the data will be stored, managed and processed within it.
+
+36
+00:03:17,000 --> 00:03:26,000
+It helps in designing a database and serves as a blueprint for application developers and database administrators
+
+37
+00:03:26,000 --> 00:03:27,000
+in creating a database.
+
+38
+00:03:28,000 --> 00:03:36,000
+You are more or less already familiar with relational data model, so relational data model is an approach
+
+39
+00:03:36,000 --> 00:03:43,000
+to managing data using a structure and language consistent with logic where all data is represented
+
+40
+00:03:43,000 --> 00:03:51,000
+in terms of tables grouped into relations, and we learn all the different types of relations in a separate
+
+41
+00:03:51,000 --> 00:03:51,000
+lesson.
+
+42
+00:03:52,000 --> 00:03:55,000
+There are three main groups of data models.
+
+43
+00:03:55,000 --> 00:03:59,000
+They are logical, conceptual and physical.
+
+44
+00:04:00,000 --> 00:04:04,000
+In this lesson, we are going to go all of them and understand the difference between them.
+
+45
+00:04:05,000 --> 00:04:11,000
+But before we even try to understand the difference between different groups of data model, let's make
+
+46
+00:04:11,000 --> 00:04:18,000
+sure that we all understand the importance of data modeling and try to understand motivations that stands
+
+47
+00:04:18,000 --> 00:04:19,000
+behind this lesson.
+
+48
+00:04:20,000 --> 00:04:29,000
+Data modeling is a process of creating a visual representation of a whole information system or parts
+
+49
+00:04:29,000 --> 00:04:33,000
+of it to communicate connections between data points and structures.
+
+50
+00:04:34,000 --> 00:04:39,000
+The goal is to illustrate the types of data used and stored within the system.
+
+51
+00:04:39,000 --> 00:04:42,000
+The relationships and ones these data types.
+
+52
+00:04:42,000 --> 00:04:48,000
+The ways that data can be grouped and organized, and its formats and attributes.
+
+53
+00:04:49,000 --> 00:04:50,000
+Why we need data modeling.
+
+54
+00:04:51,000 --> 00:04:52,000
+Can we live without it at all?
+
+55
+00:04:53,000 --> 00:04:55,000
+Well, to answer objectively.
+
+56
+00:04:56,000 --> 00:05:02,000
+But in my opinion, we can't leave without data model unions, the development of our app.
+
+57
+00:05:03,000 --> 00:05:08,000
+It is only a matter of how you will come up with a data model for your app, but you will spend some
+
+58
+00:05:08,000 --> 00:05:13,000
+time on data monitoring for sure, and it will be done in one or another way.
+
+59
+00:05:14,000 --> 00:05:20,000
+And what I like to explain this lesson is to give you standardized tools and approaches for data modeling,
+
+60
+00:05:21,000 --> 00:05:25,000
+because creating proper data models for all app, it is super important task.
+
+61
+00:05:26,000 --> 00:05:32,000
+And sometimes it is hard just to create a few tables straight away and start using specific data structures
+
+62
+00:05:32,000 --> 00:05:34,000
+and build your codes around.
+
+63
+00:05:34,000 --> 00:05:36,000
+Identify dependencies.
+
+64
+00:05:36,000 --> 00:05:41,000
+If you still can't understand how it is important, think about it.
+
+65
+00:05:41,000 --> 00:05:48,000
+Also from different than user development of application is performed by multiple developers.
+
+66
+00:05:48,000 --> 00:05:55,000
+It can be to engineers in case this is early stages of a startup and it can be significantly more engineers
+
+67
+00:05:55,000 --> 00:05:59,000
+if you already have proof of concept and the boat to start feature development.
+
+68
+00:06:00,000 --> 00:06:08,000
+Now, imagine that lack of database design and pure data modeling because the or one or even multiple
+
+69
+00:06:08,000 --> 00:06:09,000
+features.
+
+70
+00:06:09,000 --> 00:06:12,000
+How much money will you spend on salary of engineers?
+
+71
+00:06:12,000 --> 00:06:16,000
+The change also caught is it was built around this data model.
+
+72
+00:06:16,000 --> 00:06:23,000
+Definitely desert techniques of green architecture and introduction of abstraction layer in your app
+
+73
+00:06:23,000 --> 00:06:26,000
+that minimize rewriting of all persistence layer.
+
+74
+00:06:27,000 --> 00:06:35,000
+So definitely, this won't be like dramatic impact, but still sometimes changes in business model mapping
+
+75
+00:06:35,000 --> 00:06:44,000
+may impact business logic and the way how you interact with data inside your app and how you practice
+
+76
+00:06:44,000 --> 00:06:44,000
+it.
+
+77
+00:06:44,000 --> 00:06:50,000
+The ability to correct it and devise a business and adjust ends the way we want it to models.
+
+78
+00:06:50,000 --> 00:06:54,000
+Those relationships is pivotal to good information quality.
+
+79
+00:06:55,000 --> 00:07:02,000
+Most teams and other musicians opt for physical modeling and great application specific schemas that
+
+80
+00:07:02,000 --> 00:07:04,000
+often lack the high level vision.
+
+81
+00:07:04,000 --> 00:07:08,000
+So how is the business really needs to utilize its data?
+
+82
+00:07:09,000 --> 00:07:12,000
+Also, there is one more related term.
+
+83
+00:07:12,000 --> 00:07:13,000
+It is database design.
+
+84
+00:07:14,000 --> 00:07:14,000
+What is it?
+
+85
+00:07:15,000 --> 00:07:17,000
+Database design is organizational data.
+
+86
+00:07:17,000 --> 00:07:25,000
+According to database model, the designer determines what data must be stored and how the data elements
+
+87
+00:07:25,000 --> 00:07:26,000
+interrelate.
+
+88
+00:07:26,000 --> 00:07:29,000
+Database management system manages the data accordingly.
+
+89
+00:07:30,000 --> 00:07:36,000
+Database design involves classifying data and identifying interrelationships.
+
+90
+00:07:36,000 --> 00:07:41,000
+This surgical representation of the data is called an ontology.
+
+91
+00:07:41,000 --> 00:07:49,000
+The ontology is a theory behind the databases design in order to perform data more an inefficient way.
+
+92
+00:07:49,000 --> 00:07:52,000
+We need to have a clear understanding of data context.
+
+93
+00:07:53,000 --> 00:07:59,000
+You can treat data as a puzzle where a puzzle piece is a data entity.
+
+94
+00:07:59,000 --> 00:08:07,000
+If you would like me to be not so specific in concrete terms but define an abstraction instead of data
+
+95
+00:08:07,000 --> 00:08:09,000
+entity, we can use any other terms.
+
+96
+00:08:10,000 --> 00:08:18,000
+So as a piece of Basel, you can use any concept or important thing for business about which we want
+
+97
+00:08:18,000 --> 00:08:27,000
+to collect data and in order to get it pieces and in order to get the pieces to fit together, you need
+
+98
+00:08:27,000 --> 00:08:33,000
+to understand the proper relationship of the piece in question to the other puzzle pieces.
+
+99
+00:08:34,000 --> 00:08:41,000
+The conceptual data model is a picture on the puzzle books that provides a vision of what Information
+
+100
+00:08:41,000 --> 00:08:47,000
+Basel should look like at the end of the day, regardless of whether your solution is a data warehouse,
+
+101
+00:08:47,000 --> 00:08:51,000
+ERP mustard that the management or anything else.
+
+102
+00:08:52,000 --> 00:09:00,000
+Now, let's hear what the conceptual data model is, that conceptual data model is a diagram identifies
+
+103
+00:09:00,000 --> 00:09:07,000
+the business concepts well, like we usually call them, and that is also this type of data model identifies
+
+104
+00:09:07,000 --> 00:09:14,000
+the relationships between these concepts in order to gain, reflect and document understanding of the
+
+105
+00:09:14,000 --> 00:09:16,000
+organization's business from a data perspective.
+
+106
+00:09:17,000 --> 00:09:20,000
+It shows how the business world sees information.
+
+107
+00:09:21,000 --> 00:09:27,000
+It suppresses non-critical details in order to emphasize business rules and user objects.
+
+108
+00:09:28,000 --> 00:09:35,000
+It typically includes on the significant entities which have business meaning, along with their relationships
+
+109
+00:09:35,000 --> 00:09:39,000
+and conceptual data model usually takes the form of an entity.
+
+110
+00:09:39,000 --> 00:09:47,000
+Relationship diagram or object role model is a conceptual data model typically does not contain attributes
+
+111
+00:09:48,000 --> 00:09:55,000
+or if it does on the significant attributes it is important to mention is that the conceptual data model
+
+112
+00:09:55,000 --> 00:09:59,000
+is technology and application independent.
+
+113
+00:09:59,000 --> 00:10:06,000
+The conceptual data model should reflect relationships from a historical longitudinal perspective.
+
+114
+00:10:07,000 --> 00:10:13,000
+For example, a relationship between a store and employee may usually be considered as one too many,
+
+115
+00:10:14,000 --> 00:10:20,000
+but when viewed from a historical perspective, perhaps zero relationships may actually be managed.
+
+116
+00:10:20,000 --> 00:10:28,000
+Many whether the employee begins work at another store, why conceptual data model is important and
+
+117
+00:10:28,000 --> 00:10:34,000
+what issues you may encounter in case you skip trace of conceptual datum or design.
+
+118
+00:10:35,000 --> 00:10:42,000
+You may be constantly stumbling through zealots conceptual data model, but you won't see the big picture.
+
+119
+00:10:43,000 --> 00:10:49,000
+It is hard to identify and understand all possible relationships that are required and miss important
+
+120
+00:10:49,000 --> 00:10:56,000
+seems when you are down in the details of the development and new system from scratch, especially when
+
+121
+00:10:56,000 --> 00:10:59,000
+you work on some complex enterprise solution.
+
+122
+00:10:59,000 --> 00:11:08,000
+The three basic tenets of conceptual data model are entity, a real world, single attribute characteristics
+
+123
+00:11:08,000 --> 00:11:15,000
+or properties of an entity, relationship dependency or association between entities.
+
+124
+00:11:16,000 --> 00:11:20,000
+Conceptual data model, example, customer and product are two entities.
+
+125
+00:11:21,000 --> 00:11:28,000
+Customer number and name attributes of the customer, entity, product, name and price are attributes
+
+126
+00:11:28,000 --> 00:11:29,000
+of product entity.
+
+127
+00:11:29,000 --> 00:11:32,000
+Sale is a relationship between the customer and product.
+
+128
+00:11:33,000 --> 00:11:40,000
+As you can see, this is not like super detailed vision of data model, and therefore this is not ready
+
+129
+00:11:40,000 --> 00:11:46,000
+to use database that is built with the specifics of database management system and logical data model
+
+130
+00:11:46,000 --> 00:11:49,000
+is a data model of a specific problem.
+
+131
+00:11:49,000 --> 00:11:55,000
+The main expressed independently of a particular database management product or storage technology,
+
+132
+00:11:56,000 --> 00:12:03,000
+but nevertheless logical data model is visualized and described in terms of known data structures.
+
+133
+00:12:03,000 --> 00:12:10,000
+For example, logical data model may be described as relational tables and columns, object oriented
+
+134
+00:12:10,000 --> 00:12:12,000
+colossus or similar tax.
+
+135
+00:12:13,000 --> 00:12:18,000
+Sometimes in the literature, you may find that it is referred as logical schema.
+
+136
+00:12:19,000 --> 00:12:26,000
+Logical database design describes the data without any details of how exactly this data will be physically
+
+137
+00:12:26,000 --> 00:12:27,000
+implemented.
+
+138
+00:12:27,000 --> 00:12:35,000
+This database and logical data models It is worse to highlight the next once hierarchical database model.
+
+139
+00:12:36,000 --> 00:12:39,000
+It is the oldest form of database model.
+
+140
+00:12:39,000 --> 00:12:43,000
+It was developed by IBM for Information Management System.
+
+141
+00:12:44,000 --> 00:12:47,000
+It is a set of organized data into structure.
+
+142
+00:12:48,000 --> 00:12:53,000
+DB Record is a three and system of many groups called segments.
+
+143
+00:12:54,000 --> 00:12:56,000
+It uses one to many relationships.
+
+144
+00:12:56,000 --> 00:12:59,000
+The data access is also predictable.
+
+145
+00:13:00,000 --> 00:13:01,000
+Network model.
+
+146
+00:13:02,000 --> 00:13:08,000
+It is a database model conceived as a flexible way of representing objects and their relationships.
+
+147
+00:13:08,000 --> 00:13:17,000
+It's distinguishing feature is that the schema used as a graph in which object types and loads and the
+
+148
+00:13:17,000 --> 00:13:19,000
+relationship types are arcs.
+
+149
+00:13:20,000 --> 00:13:26,000
+It is not restricted to being a hierarchy, a lattice relational model.
+
+150
+00:13:27,000 --> 00:13:33,000
+This is probably one of the most popular data models nowadays, where all data is represented in terms
+
+151
+00:13:33,000 --> 00:13:40,000
+of doubles grouped into relations, and that your relationship model just collapse into the later things
+
+152
+00:13:40,000 --> 00:13:41,000
+of interest.
+
+153
+00:13:42,000 --> 00:13:49,000
+The specific domain of knowledge and basic our model is composed of an entity, Typekit, which classifies
+
+154
+00:13:49,000 --> 00:13:55,000
+as things of interest and specifies relationships that can exist between entities.
+
+155
+00:13:55,000 --> 00:13:57,000
+You can see that on diagram.
+
+156
+00:13:57,000 --> 00:14:04,000
+It is super easy to understand relationships between entities because of reasonable way of depicting
+
+157
+00:14:04,000 --> 00:14:06,000
+all connections and their types.
+
+158
+00:14:07,000 --> 00:14:08,000
+Object model.
+
+159
+00:14:08,000 --> 00:14:15,000
+It is a database management system in which information is represented in the form of object as used
+
+160
+00:14:15,000 --> 00:14:17,000
+in object oriented programming.
+
+161
+00:14:17,000 --> 00:14:22,000
+Object databases are different from relational database, which are table oriented.
+
+162
+00:14:23,000 --> 00:14:26,000
+Object or relational database is a hybrid of both approaches.
+
+163
+00:14:27,000 --> 00:14:35,000
+Documents model, this is data storage system designed for storing, retrieving and managing documents
+
+164
+00:14:35,000 --> 00:14:39,000
+oriented information, also known as semi-structured data.
+
+165
+00:14:39,000 --> 00:14:46,000
+And if you remember our lesson about overview of different database management systems Xeni should remember
+
+166
+00:14:46,000 --> 00:14:53,000
+is a document model is probably one of the main data models that is used in the design of NoSQL database.
+
+167
+00:14:54,000 --> 00:14:56,000
+Entity attributes value model.
+
+168
+00:14:56,000 --> 00:15:03,000
+It is a data model to encode in a space efficient manner, and that is where a number of attributes,
+
+169
+00:15:04,000 --> 00:15:11,000
+properties parameters can be used to describe them is potentially vast, but the numbers it will actually
+
+170
+00:15:11,000 --> 00:15:14,000
+apply to even entity is relatively modest.
+
+171
+00:15:15,000 --> 00:15:22,000
+Such entities correspond to the mathematical notion of sparse markets star schema.
+
+172
+00:15:23,000 --> 00:15:30,000
+It is the simplest style of data more schema and is the approach most widely used to develop data warehouses
+
+173
+00:15:30,000 --> 00:15:32,000
+and dimensional data models.
+
+174
+00:15:33,000 --> 00:15:40,000
+Logical data model is as opposed to a conceptual data model, which describes the semantics of an organization
+
+175
+00:15:40,000 --> 00:15:42,000
+without reference to technology.
+
+176
+00:15:43,000 --> 00:15:46,000
+Logical models are often that romantic in nature.
+
+177
+00:15:47,000 --> 00:15:48,000
+When are they used?
+
+178
+00:15:49,000 --> 00:15:52,000
+Usually, they're most used in business processes.
+
+179
+00:15:53,000 --> 00:16:00,000
+Once validated and approved, the logical data model becomes the basis of a physical data model and
+
+180
+00:16:00,000 --> 00:16:02,000
+for the design of a database.
+
+181
+00:16:02,000 --> 00:16:10,000
+The term logical data model is sometimes used as a synonym of the mean model or as an alternative to
+
+182
+00:16:10,000 --> 00:16:11,000
+the mean model.
+
+183
+00:16:12,000 --> 00:16:19,000
+While the two concepts are closely related and have overlapping goals and the main model is more focused
+
+184
+00:16:19,000 --> 00:16:21,000
+on capturing the concepts, it a problem.
+
+185
+00:16:21,000 --> 00:16:30,000
+The main residence structure of the data associated with the main zoological data model is used to define
+
+186
+00:16:30,000 --> 00:16:35,000
+the structure of data elements and to set relationships between them.
+
+187
+00:16:36,000 --> 00:16:41,000
+Zoological data model adds further information to the conceptual data model elements.
+
+188
+00:16:41,000 --> 00:16:48,000
+The advantage of using a logical data model is to provide the foundation, the forms, the base for
+
+189
+00:16:48,000 --> 00:16:49,000
+the physical model.
+
+190
+00:16:50,000 --> 00:16:53,000
+However, the model structure remains generic.
+
+191
+00:16:54,000 --> 00:17:00,000
+The next things that we are going to learn today is to learn more about the group of physical data models.
+
+192
+00:17:01,000 --> 00:17:08,000
+Let's start from the definition the physical data model is a representation of a data design as implemented
+
+193
+00:17:08,000 --> 00:17:12,000
+or intended to be implemented in a database management system.
+
+194
+00:17:13,000 --> 00:17:20,000
+The feel right is a difference between conceptual and logical data models in the lifecycle of a project.
+
+195
+00:17:20,000 --> 00:17:24,000
+It typically derives from a logical data model.
+
+196
+00:17:24,000 --> 00:17:29,000
+So it may be reverse engineered from a given database implementation.
+
+197
+00:17:29,000 --> 00:17:36,000
+A complete physical data model will include all the database artifacts required, the great relationships
+
+198
+00:17:36,000 --> 00:17:45,000
+between tables or to achieve performance goals such as indexes considering definitions, Lincoln tables,
+
+199
+00:17:45,000 --> 00:17:47,000
+partition tables or clusters.
+
+200
+00:17:48,000 --> 00:17:53,000
+Physical database design represents how the actual database is built in.
+
+201
+00:17:53,000 --> 00:17:59,000
+The first lesson of my course about databases you learned the most popular database management systems.
+
+202
+00:18:00,000 --> 00:18:05,000
+Please refer to that lesson if you want to check specific names and database management systems.
+
+203
+00:18:05,000 --> 00:18:14,000
+There are two main physical data models Inverted Index, and that file inverted index that is also referred
+
+204
+00:18:14,000 --> 00:18:23,000
+to as a custom file or inverted file, is a database in storing and mapping some content, such as words
+
+205
+00:18:23,000 --> 00:18:30,000
+or numbers, to its location, in a table or in a document, or in a set of documents.
+
+206
+00:18:30,000 --> 00:18:35,000
+In this course, you also can find less about indexes and how to book with them.
+
+207
+00:18:36,000 --> 00:18:41,000
+In that lesson, we discuss specifics of interaction with index from its creation until its removal.
+
+208
+00:18:42,000 --> 00:18:50,000
+The purpose of an inverted index is to allow fast, full text searches at the cost of increased processing.
+
+209
+00:18:50,000 --> 00:18:54,000
+When a document would just in Utah, Apple is added to the database.
+
+210
+00:18:54,000 --> 00:19:01,000
+So basically the performance of reading and searching data will be better and will be executed faster.
+
+211
+00:19:02,000 --> 00:19:07,000
+But on the other hand, operations of insertion will take more time.
+
+212
+00:19:07,000 --> 00:19:15,000
+That is because after adding additional rule, autoplay indexes needed to be recalculated to stay sorted
+
+213
+00:19:15,000 --> 00:19:23,000
+and ensure logarithmic connotation for extraction operations, zingers at file may be a database file
+
+214
+00:19:23,000 --> 00:19:25,000
+itself rather than its index.
+
+215
+00:19:26,000 --> 00:19:32,000
+It is the most popular data structure used in document retrieval systems used on the large scale.
+
+216
+00:19:32,000 --> 00:19:35,000
+For example, in search engines.
+
+217
+00:19:35,000 --> 00:19:42,000
+On the other hand, a flat file database is a database stored in the file called a flat file.
+
+218
+00:19:43,000 --> 00:19:50,000
+Records follow a uniform format, and there are no structure for indexing or recognizing relationships
+
+219
+00:19:50,000 --> 00:19:51,000
+between records.
+
+220
+00:19:51,000 --> 00:19:57,000
+This file is simple a flat file can be a plain text file or a binary file.
+
+221
+00:19:58,000 --> 00:20:06,000
+Relationships can be inferred from the data in the database, but the database format itself doesn't
+
+222
+00:20:06,000 --> 00:20:08,000
+make those relationships explicit.
+
+223
+00:20:08,000 --> 00:20:16,000
+The term has generally implied a small database, but very large that the basis can also be flat.
+
+224
+00:20:16,000 --> 00:20:23,000
+If you want an example of a flat file database, you can imagine Linnaeus thought of the sequel data.
+
+225
+00:20:24,000 --> 00:20:29,000
+A physical dating model describes that the base specific implementation of the data model.
+
+226
+00:20:29,000 --> 00:20:34,000
+It offers database abstraction and helps generate the schema.
+
+227
+00:20:34,000 --> 00:20:41,000
+The main difference between logical database design and physical database design is that logical database
+
+228
+00:20:41,000 --> 00:20:45,000
+design helps to define the data elements and their relationships.
+
+229
+00:20:46,000 --> 00:20:52,000
+But physical database design helps to design the actual database based on the requirements gathered
+
+230
+00:20:52,000 --> 00:20:56,000
+doing the logical data design and conceptual data design.
+
+231
+00:20:57,000 --> 00:21:04,000
+We learned what conceptual data model, logical data model and physical data model is to help you understand
+
+232
+00:21:04,000 --> 00:21:06,000
+better the difference between all of these.
+
+233
+00:21:07,000 --> 00:21:09,000
+I want to present use of current slide.
+
+234
+00:21:10,000 --> 00:21:16,000
+So let's recap in one sentence about each type of data model's conceptual data model.
+
+235
+00:21:17,000 --> 00:21:20,000
+This data model defines what the system contains.
+
+236
+00:21:21,000 --> 00:21:26,000
+This model is typically created by business stakeholders and data architects.
+
+237
+00:21:26,000 --> 00:21:32,000
+The purpose is to organize, scope and define business concepts and rules.
+
+238
+00:21:32,000 --> 00:21:39,000
+Logical data model defines how the system should be implemented regardless of the database management
+
+239
+00:21:39,000 --> 00:21:39,000
+system.
+
+240
+00:21:40,000 --> 00:21:45,000
+This model is typically created by data architects and business analysts.
+
+241
+00:21:45,000 --> 00:21:50,000
+The purpose is to develop a technical map of rules and data structures.
+
+242
+00:21:51,000 --> 00:21:58,000
+Physical data model This data model describes how the system will be implemented using a specific database
+
+243
+00:21:58,000 --> 00:21:59,000
+management system.
+
+244
+00:22:00,000 --> 00:22:04,000
+This model is typically created by database architects and developers.
+
+245
+00:22:05,000 --> 00:22:08,000
+The purpose is actual implementation of the database.
+
+246
+00:22:09,000 --> 00:22:15,000
+A conceptual data model identifies the highest level relationships between the different, and that
+
+247
+00:22:15,000 --> 00:22:22,000
+these features of conceptual data model include the important entities and the relationships among them.
+
+248
+00:22:23,000 --> 00:22:24,000
+No attribute is specified.
+
+249
+00:22:24,000 --> 00:22:26,000
+No primary key is specified.
+
+250
+00:22:27,000 --> 00:22:35,000
+A logical data model describes the data in as much detail as possible without regard to how they will
+
+251
+00:22:35,000 --> 00:22:37,000
+be physically implemented in the database.
+
+252
+00:22:37,000 --> 00:22:44,000
+Features of logical data model include all entities and relationships, and also all attributes for
+
+253
+00:22:44,000 --> 00:22:50,000
+each entity are specified is a primary key for each entity is specified.
+
+254
+00:22:50,000 --> 00:22:55,000
+Foreign keys incident defines the relationship between different entities.
+
+255
+00:22:55,000 --> 00:22:59,000
+A specified normalization occurs at this level.
+
+256
+00:23:00,000 --> 00:23:06,000
+The steps for design and the logical data model are as follows Specified primary keys for all entities
+
+257
+00:23:07,000 --> 00:23:09,000
+find the relationships between different entities.
+
+258
+00:23:10,000 --> 00:23:12,000
+Find all attributes for each entity.
+
+259
+00:23:13,000 --> 00:23:17,000
+Resolve many to many relationships normalization.
+
+260
+00:23:17,000 --> 00:23:20,000
+You can learn more about normalization from other lessons.
+
+261
+00:23:20,000 --> 00:23:26,000
+Of course, this is also a very important topic, and I dedicated a lot of time and attention to it.
+
+262
+00:23:27,000 --> 00:23:34,000
+Physical data model represents how the model will be built into database, a physical database model
+
+263
+00:23:34,000 --> 00:23:41,000
+shows all table structures, including column name, column data, type, column constraints, primary
+
+264
+00:23:41,000 --> 00:23:45,000
+key, foreign key and relationships between tables.
+
+265
+00:23:46,000 --> 00:23:51,000
+Features of a physical data model include specification of all tables and columns.
+
+266
+00:23:52,000 --> 00:23:55,000
+Foreign keys are used to identify relationships between tables.
+
+267
+00:23:56,000 --> 00:24:00,000
+The normalization may occur based on user requirements.
+
+268
+00:24:00,000 --> 00:24:06,000
+If you don't know what the normalization is, please refer to the lesson about normalization and normal
+
+269
+00:24:06,000 --> 00:24:09,000
+forms in scope of that lesson.
+
+270
+00:24:09,000 --> 00:24:12,000
+I also described what normalization is.
+
+271
+00:24:13,000 --> 00:24:18,000
+Physical considerations may cause the physical data model to be quite different from the logical data
+
+272
+00:24:18,000 --> 00:24:19,000
+model.
+
+273
+00:24:19,000 --> 00:24:24,000
+Physical data model will be different for different database management systems.
+
+274
+00:24:24,000 --> 00:24:32,000
+For example, data type for a call made the difference between Oracle and DB two, and also there might
+
+275
+00:24:32,000 --> 00:24:33,000
+be other differences.
+
+276
+00:24:33,000 --> 00:24:41,000
+The steps for physical data modal design are as follows Converged entities into tables convert relationships
+
+277
+00:24:41,000 --> 00:24:45,000
+into foreign keys, convert attributes into columns.
+
+278
+00:24:46,000 --> 00:24:50,000
+Modifies the physical data model based on physical constraints.
+
+279
+00:24:50,000 --> 00:24:50,000
+Mark ones.
+
+280
+00:24:51,000 --> 00:24:53,000
+That's all what I wanted to share with you today.
+
+281
+00:24:54,000 --> 00:24:57,000
+You learned a lot of important and interesting things today.
+
+282
+00:24:58,000 --> 00:25:01,000
+Let's review what we have learned in this lesson.
+
+283
+00:25:01,000 --> 00:25:06,000
+We learned what data model and that the base model is what discussed.
+
+284
+00:25:06,000 --> 00:25:08,000
+What database design is.
+
+285
+00:25:08,000 --> 00:25:12,000
+Also, we discussed and understood the importance of data modeling process.
+
+286
+00:25:13,000 --> 00:25:15,000
+After this lesson, you know what?
+
+287
+00:25:15,000 --> 00:25:20,000
+Data context is relative used and learned three main groups of data models.
+
+288
+00:25:21,000 --> 00:25:25,000
+They are conceptual, logical and physical data models.
+
+289
+00:25:26,000 --> 00:25:28,000
+Thanks a lot for your attention.
+
+290
+00:25:28,000 --> 00:25:31,000
+Have a great day and see you in the next lesson.
+

51 - ===== SQL Homework Online Shop =====/001 Homework-with-links-to-solution.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://docs.google.com/document/d/10Wz-j_aerkD-Z9A4reYYp9nPS69NF19w71Fq6YU-M50/edit?usp=sharing

51 - ===== SQL Homework Online Shop =====/001 SQL Homework Task and Solution Review_en.srt

@@ -0,0 +1,400 @@
+1
+00:00:06,000 --> 00:00:06,000
+Hello, Jim.
+
+2
+00:00:07,000 --> 00:00:11,000
+In this video, we're going to review with you your home tasks, the task that I'm going to share with
+
+3
+00:00:11,000 --> 00:00:15,000
+your supposed to help you learn and understand school topic matter.
+
+4
+00:00:16,000 --> 00:00:22,000
+If you are students of my Java from zero, the first job course, you should already know that you're
+
+5
+00:00:22,000 --> 00:00:23,000
+in the course.
+
+6
+00:00:23,000 --> 00:00:26,000
+We work on creation of our own online shop.
+
+7
+00:00:26,000 --> 00:00:31,000
+We also need to have a database to support main operations in our online shop.
+
+8
+00:00:32,000 --> 00:00:38,000
+That's why in today's homework, we are going to have ecommerce terminology anyway.
+
+9
+00:00:38,000 --> 00:00:43,000
+I believe this will be interesting for you because the whole tasks that I would ask you to implement
+
+10
+00:00:43,000 --> 00:00:46,000
+are closely related to real life examples.
+
+11
+00:00:47,000 --> 00:00:52,000
+And the first things that you need to do is to make sure that you have all necessary tables to execute
+
+12
+00:00:52,000 --> 00:00:59,000
+queries from your home, tasks to help you create all necessary tables, foster and populate data.
+
+13
+00:00:59,000 --> 00:01:04,000
+I prepared a special script for you that you just need to execute in your database.
+
+14
+00:01:05,000 --> 00:01:10,000
+Just open this link, copy the script and execute it in your database.
+
+15
+00:01:11,000 --> 00:01:17,000
+Once this script will be executed, you will notice that five tables created in your database take your
+
+16
+00:01:17,000 --> 00:01:19,000
+time to explore those tables.
+
+17
+00:01:19,000 --> 00:01:21,000
+This structure and they things out.
+
+18
+00:01:22,000 --> 00:01:25,000
+Pay attention to the type of the relationships between different entities.
+
+19
+00:01:26,000 --> 00:01:31,000
+Once you have all necessary tables and data in it, we are ready to proceed with home tasks.
+
+20
+00:01:32,000 --> 00:01:38,000
+The first task is to select distinct emails of users who made at least one purchase.
+
+21
+00:01:39,000 --> 00:01:41,000
+Basically, nuts in this complex here.
+
+22
+00:01:42,000 --> 00:01:47,000
+This query was required to create joint query to two tables, purchases and user.
+
+23
+00:01:48,000 --> 00:01:53,000
+The second task would be to create SQL queries that will select product names and purchase ideas for
+
+24
+00:01:53,000 --> 00:01:54,000
+each purchase.
+
+25
+00:01:55,000 --> 00:02:00,000
+Set tasks to create sequel statement to select credit card and product name.
+
+26
+00:02:01,000 --> 00:02:06,000
+You should select credit cards as it was used for purchase of this specific product.
+
+27
+00:02:07,000 --> 00:02:14,000
+One more task is to select last name of user and total amount of purchases made by this user.
+
+28
+00:02:14,000 --> 00:02:16,000
+This is going to be a really interesting one.
+
+29
+00:02:17,000 --> 00:02:22,000
+Select less name of user and total amount of purchases made by this user.
+
+30
+00:02:22,000 --> 00:02:26,000
+Only for users who make two or more purchases.
+
+31
+00:02:27,000 --> 00:02:33,000
+And last but not least, task is to select total amount of money user already spent in our store.
+
+32
+00:02:34,000 --> 00:02:41,000
+As you can see, I tried to come up with real life business cases by implementing this squarish.
+
+33
+00:02:41,000 --> 00:02:44,000
+You will be able to practice your knowledge in aggregate functions.
+
+34
+00:02:44,000 --> 00:02:49,000
+Junqueras groupings are results, applying different conditions and so on.
+
+35
+00:02:50,000 --> 00:02:52,000
+Don't hurry up to check my solution.
+
+36
+00:02:53,000 --> 00:02:56,000
+Try to take your time and come up with your solution first.
+
+37
+00:02:57,000 --> 00:03:04,000
+Try to create queries by analogy because during the course, we already created similar queries in some
+
+38
+00:03:04,000 --> 00:03:04,000
+tasks.
+
+39
+00:03:04,000 --> 00:03:11,000
+From the least, you may need to have multiple joints, press, pause, and once you are done with your
+
+40
+00:03:11,000 --> 00:03:13,000
+solution, resumes the video.
+
+41
+00:03:13,000 --> 00:03:18,000
+And let's compare my and your solution in the first task.
+
+42
+00:03:18,000 --> 00:03:23,000
+I use distinct keywords to extract only distinct user emails.
+
+43
+00:03:24,000 --> 00:03:32,000
+I use joint statement to make joint query on purchase table to make sure that I extract only users that
+
+44
+00:03:32,000 --> 00:03:34,000
+have associated records in purchased table.
+
+45
+00:03:35,000 --> 00:03:40,000
+I use foreign key in purchased table to map records between two tables.
+
+46
+00:03:41,000 --> 00:03:43,000
+Here we have one too many relationships.
+
+47
+00:03:44,000 --> 00:03:50,000
+That's why there is no need in this table, and we can easily implement this relationship with the help
+
+48
+00:03:50,000 --> 00:03:52,000
+of foreign key and purchase table.
+
+49
+00:03:52,000 --> 00:03:53,000
+Does it make sense?
+
+50
+00:03:54,000 --> 00:03:56,000
+Is everything clear so far?
+
+51
+00:03:57,000 --> 00:04:03,000
+And by the way, team, as always, in case you have any questions, please do not hesitate to put your
+
+52
+00:04:03,000 --> 00:04:07,000
+questions and comments below this video, and I will be happy to answer those.
+
+53
+00:04:08,000 --> 00:04:15,000
+Second task is almost similar to the first one in terms that we create joint statements two two tables
+
+54
+00:04:15,000 --> 00:04:16,000
+only.
+
+55
+00:04:16,000 --> 00:04:24,000
+We need to extract information about product and we can extracted from product table and to verify in
+
+56
+00:04:24,000 --> 00:04:26,000
+which purchase this product was purchased.
+
+57
+00:04:27,000 --> 00:04:30,000
+We need to check this in purchased product table.
+
+58
+00:04:31,000 --> 00:04:34,000
+In the search task, we need to create multiple joints.
+
+59
+00:04:34,000 --> 00:04:35,000
+Why?
+
+60
+00:04:35,000 --> 00:04:42,000
+Because we need to extract credit card value that is stored in user table and product names at the storage
+
+61
+00:04:42,000 --> 00:04:43,000
+product table.
+
+62
+00:04:43,000 --> 00:04:49,000
+But to identify which shoes are bought, which products, we need to query purchase table.
+
+63
+00:04:49,000 --> 00:04:53,000
+Because some purchase table, there is an info about users purchases.
+
+64
+00:04:54,000 --> 00:05:00,000
+But to understand which product has been purchased in scope of which purchase, we need to query purchase
+
+65
+00:05:00,000 --> 00:05:06,000
+product table because there is many, too many relationships between product and purchase.
+
+66
+00:05:07,000 --> 00:05:10,000
+Each purchase may consist of multiple products, correct?
+
+67
+00:05:11,000 --> 00:05:17,000
+During the one session, I can buy a laptop and separate keyboards, for example, and each product
+
+68
+00:05:17,000 --> 00:05:19,000
+may be purchased many times.
+
+69
+00:05:19,000 --> 00:05:24,000
+We have hundreds of the same keyboards, or we have hundreds of similar laptops.
+
+70
+00:05:25,000 --> 00:05:30,000
+That's why to implement many to many relationships, one needs a smart table.
+
+71
+00:05:30,000 --> 00:05:37,000
+And in this particular case, we also need to include it in our joint statement to get information that
+
+72
+00:05:37,000 --> 00:05:37,000
+we need.
+
+73
+00:05:38,000 --> 00:05:45,000
+We need to specify conditions that will allow us to map records between different tables, including
+
+74
+00:05:45,000 --> 00:05:46,000
+product table.
+
+75
+00:05:46,000 --> 00:05:50,000
+And when we execute this query, we receive what we expect.
+
+76
+00:05:51,000 --> 00:05:57,000
+In the first task, we are going to use aggregate function to count total number of purchases made by
+
+77
+00:05:57,000 --> 00:06:04,000
+each user after we made select statement to retrieve required information from user and purchase tables.
+
+78
+00:06:04,000 --> 00:06:09,000
+We need to group results by each user in this particular example.
+
+79
+00:06:09,000 --> 00:06:12,000
+I want to group results my last name.
+
+80
+00:06:13,000 --> 00:06:19,000
+You can use analysis if you wish, but probably you already noticed that I use them in all my queries
+
+81
+00:06:19,000 --> 00:06:23,000
+because I used to do them and I find this comfortable.
+
+82
+00:06:24,000 --> 00:06:25,000
+One query is executed.
+
+83
+00:06:26,000 --> 00:06:35,000
+We use user's last name mapped to the total amount of purchases he or she made in our online store in
+
+84
+00:06:35,000 --> 00:06:36,000
+the fifth task.
+
+85
+00:06:36,000 --> 00:06:40,000
+We are going to use the same query as in for stock with small additions.
+
+86
+00:06:40,000 --> 00:06:44,000
+We need to add conditions that will have only records that we need.
+
+87
+00:06:45,000 --> 00:06:47,000
+That's why I have to go by.
+
+88
+00:06:47,000 --> 00:06:53,000
+I write have in close to leaf only users that have more or equal to do purchases.
+
+89
+00:06:54,000 --> 00:06:54,000
+Is it clear?
+
+90
+00:06:55,000 --> 00:06:59,000
+In the six, Starsk, we also use aggregate function.
+
+91
+00:06:59,000 --> 00:07:05,000
+This time we need to find total money amount spent in our online shop by each user.
+
+92
+00:07:06,000 --> 00:07:12,000
+For this, I use some aggregate function to some price of all products that have been purchased by our
+
+93
+00:07:12,000 --> 00:07:13,000
+user.
+
+94
+00:07:14,000 --> 00:07:17,000
+And the same logic we have discussed is applied here.
+
+95
+00:07:18,000 --> 00:07:24,000
+We need to make multiple joints to map all records between each other to extract information we need.
+
+96
+00:07:24,000 --> 00:07:28,000
+In this example, I group result by user last name.
+
+97
+00:07:29,000 --> 00:07:36,000
+Basically, that's all my solution, and that's all homework review, hope that this figure was helpful
+
+98
+00:07:36,000 --> 00:07:41,000
+for you to rack up knowledge nerd in this course and as a reset.
+
+99
+00:07:42,000 --> 00:07:46,000
+Feel free to ask questions in case of any thanks a lot for your attention.
+
+100
+00:07:46,000 --> 00:07:49,000
+Have a great day and see you in the next lesson.
+

51 - ===== SQL Homework Online Shop =====/external-links.txt

@@ -0,0 +1,3 @@
+
+001 Homework-with-links-to-solution
+https://docs.google.com/document/d/10Wz-j_aerkD-Z9A4reYYp9nPS69NF19w71Fq6YU-M50/edit?usp=sharing

52 - JDBC/001 JDBC Overview Establish connection with DB from Java App_en.srt

@@ -0,0 +1,988 @@
+1
+00:00:06,000 --> 00:00:11,000
+Hello, yes, tenants, I'm happy to announce that the day will start super important topic, we are
+
+2
+00:00:11,000 --> 00:00:12,000
+going to learn the ABC.
+
+3
+00:00:13,000 --> 00:00:17,000
+Definitely it will be hard to learn all to this topic and one single lesson.
+
+4
+00:00:17,000 --> 00:00:23,000
+But the day where I learned to learn basic concepts about the ABC understand what it is.
+
+5
+00:00:23,000 --> 00:00:29,000
+And the first practical exercise to establish connection is a database from our Java program.
+
+6
+00:00:30,000 --> 00:00:37,000
+Since this is our first lesson about GBC will start from GBC overview to help you understand what it
+
+7
+00:00:37,000 --> 00:00:38,000
+is and why we need it.
+
+8
+00:00:39,000 --> 00:00:46,000
+After that, we are going to review different GDC driver types to make sure you understand more about
+
+9
+00:00:46,000 --> 00:00:47,000
+database connectivity.
+
+10
+00:00:47,000 --> 00:00:51,000
+I believe it is important to you and learn what Odyssey is.
+
+11
+00:00:52,000 --> 00:00:57,000
+I want to make sure that after this lesson, you understand how the book works.
+
+12
+00:00:57,000 --> 00:01:05,000
+After this piece will jump to practical exercises, we'll learn how to add a driver into the Java app
+
+13
+00:01:06,000 --> 00:01:11,000
+will establish with your connections as a database to make sure that our environment is ready for the
+
+14
+00:01:11,000 --> 00:01:11,000
+next lessons.
+
+15
+00:01:12,000 --> 00:01:14,000
+We have a lot of things to learn today.
+
+16
+00:01:14,000 --> 00:01:15,000
+Let's start.
+
+17
+00:01:16,000 --> 00:01:22,000
+Let's start today from understanding of what you did, this is genuine persistence for Java that the
+
+18
+00:01:22,000 --> 00:01:29,000
+basic connectivity see API implementation used for connecting to a particular type of a database.
+
+19
+00:01:30,000 --> 00:01:36,000
+It is a standard Java API for database and dependent connectivity between the Java programming language
+
+20
+00:01:37,000 --> 00:01:40,000
+and the wide range of databases in similar words.
+
+21
+00:01:41,000 --> 00:01:48,000
+It is a set of glasses and interfaces that allows Java programs to send sequel statements to database.
+
+22
+00:01:48,000 --> 00:01:49,000
+Why is this a standard?
+
+23
+00:01:50,000 --> 00:01:56,000
+Imagine that you have a lot of different Java programs and also you have a lot of different relational
+
+24
+00:01:56,000 --> 00:01:57,000
+database management systems.
+
+25
+00:01:58,000 --> 00:02:04,000
+The question is, should we use unique application programming interface of each relational database
+
+26
+00:02:04,000 --> 00:02:06,000
+management system to perform operations?
+
+27
+00:02:06,000 --> 00:02:13,000
+Was it different protocols and other specifics, for example, unique masses for establishing connection,
+
+28
+00:02:14,000 --> 00:02:20,000
+unique way to execute SQL queries, unique way to read and modify resulting records, and so on.
+
+29
+00:02:20,000 --> 00:02:21,000
+No way.
+
+30
+00:02:22,000 --> 00:02:29,000
+That's why Community Camp was API standard for Java applications to interact with databases, namely
+
+31
+00:02:30,000 --> 00:02:38,000
+set of interfaces, set of masses and once community agreed on the GDC API, each provider of relation
+
+32
+00:02:38,000 --> 00:02:43,000
+that the waste management system provided its own implementation of GDC Driver.
+
+33
+00:02:43,000 --> 00:02:54,000
+So GDC API is just a standard set of API interfaces, and GDC Driver is a concrete implementation is
+
+34
+00:02:54,000 --> 00:03:01,000
+a clear and thus become area of interest of database providers to create implementation of GDC API,
+
+35
+00:03:02,000 --> 00:03:07,000
+because Java getting a lot of popularity and common unique solution was needed.
+
+36
+00:03:07,000 --> 00:03:11,000
+You know that Java could interact with database management system provided.
+
+37
+00:03:12,000 --> 00:03:16,000
+Z, different bus driver types, let's review each of them one by one.
+
+38
+00:03:17,000 --> 00:03:23,000
+The first time that I'd like to describe contains a mapping to another data access API.
+
+39
+00:03:23,000 --> 00:03:25,000
+It is a database driver implementations.
+
+40
+00:03:25,000 --> 00:03:30,000
+It employs the B C driver to connect to the database.
+
+41
+00:03:31,000 --> 00:03:34,000
+The driver converts B C mass it calls into audio.
+
+42
+00:03:34,000 --> 00:03:38,000
+B C function calls logical question from your cycle.
+
+43
+00:03:38,000 --> 00:03:41,000
+B What is or d b c driver?
+
+44
+00:03:42,000 --> 00:03:43,000
+And this is a good question.
+
+45
+00:03:43,000 --> 00:03:46,000
+What do you b c stands for open database connectivity.
+
+46
+00:03:47,000 --> 00:03:52,000
+It is a standard application programming interface for accessing database management systems.
+
+47
+00:03:52,000 --> 00:04:00,000
+The designers of or D B C aims to make it independent of database systems and operating systems, and
+
+48
+00:04:00,000 --> 00:04:07,000
+application written using on the B C can be reported to other platforms both on the client and server
+
+49
+00:04:07,000 --> 00:04:10,000
+side, with few changes to the data access code.
+
+50
+00:04:11,000 --> 00:04:18,000
+What a b c was originally developed by Microsoft and Simba Technologies during the early 1990s.
+
+51
+00:04:19,000 --> 00:04:27,000
+The driver is platform dependent as it makes use of Oadby C, which in turn depends on native libraries
+
+52
+00:04:27,000 --> 00:04:30,000
+of the underlying operating systems the GVM is running.
+
+53
+00:04:30,000 --> 00:04:34,000
+The full advantage of this type of driver is obvious.
+
+54
+00:04:34,000 --> 00:04:42,000
+Almost any database for which the only B C driver is installed can be accessed and data can be retrieved.
+
+55
+00:04:43,000 --> 00:04:48,000
+Regarding the disadvantages of this type of drama, it is worse than the names of fallen ones that ought
+
+56
+00:04:48,000 --> 00:04:49,000
+to be seen.
+
+57
+00:04:49,000 --> 00:04:54,000
+Driver needs to be installed on the client machine performance of her hat sends.
+
+58
+00:04:54,000 --> 00:05:01,000
+The calls have to go so the GBC bridge to the only busy driver centres, a native database connectivity
+
+59
+00:05:01,000 --> 00:05:05,000
+interface thus may be slower than other types of drivers.
+
+60
+00:05:06,000 --> 00:05:10,000
+Specifically, busy drivers are not always available on all platforms.
+
+61
+00:05:11,000 --> 00:05:14,000
+Hence, visibility of this driver is limited.
+
+62
+00:05:15,000 --> 00:05:17,000
+No support from Jarvis and A.
+
+63
+00:05:18,000 --> 00:05:24,000
+The second type of driver is an implementation that uses client side libraries of the target database.
+
+64
+00:05:25,000 --> 00:05:28,000
+It is also called a native API driver.
+
+65
+00:05:28,000 --> 00:05:33,000
+The driver converts semester's calls into native course of the database API.
+
+66
+00:05:34,000 --> 00:05:38,000
+For example, Oracle or assigned driver, is a Typekit driver.
+
+67
+00:05:39,000 --> 00:05:44,000
+We've got an advantage as we can see that performance is better than a type number one driver.
+
+68
+00:05:44,000 --> 00:05:51,000
+That is because there is no implementation of GDP C or D B C reach, but it is also has numerous of
+
+69
+00:05:51,000 --> 00:05:52,000
+disadvantages.
+
+70
+00:05:52,000 --> 00:05:58,000
+Some of them are the vendor client library needs to be installed on the client machine.
+
+71
+00:05:59,000 --> 00:06:06,000
+Not all databases have a client side line, but this driver is a platform dependent type.
+
+72
+00:06:06,000 --> 00:06:12,000
+Number three uses middleware to convert GBC calls into database specific calls.
+
+73
+00:06:12,000 --> 00:06:21,000
+Also known as a network protocol driver is the middle tyre application server converts because directly
+
+74
+00:06:21,000 --> 00:06:24,000
+or indirectly into vendor specific database protocol.
+
+75
+00:06:25,000 --> 00:06:33,000
+This differs from the type for driver in that the protocol conversion logic resides not a decline.
+
+76
+00:06:33,000 --> 00:06:41,000
+Buttons and middle tyre like type for drivers is a type suite driver is written entirely in Java.
+
+77
+00:06:42,000 --> 00:06:48,000
+Advantages of this type of driver are the following ones since the communication between the client
+
+78
+00:06:48,000 --> 00:06:51,000
+and the middle server is database dependent.
+
+79
+00:06:51,000 --> 00:06:58,000
+There is no need for the database when the library on the client is a client needs not to be changed
+
+80
+00:06:58,000 --> 00:06:59,000
+for a new database.
+
+81
+00:07:00,000 --> 00:07:07,000
+Let me go where Sarah can provide typical middleware services like caching of connections, query results,
+
+82
+00:07:08,000 --> 00:07:16,000
+et cetera, load balancing, logging and auditing a single driver can handle any database provided some
+
+83
+00:07:16,000 --> 00:07:17,000
+the middle less courses.
+
+84
+00:07:18,000 --> 00:07:20,000
+I'm on disadvantages of this type of drama.
+
+85
+00:07:20,000 --> 00:07:26,000
+We shouldn't forget about the next ones, requires database specific coding to be done in the middle
+
+86
+00:07:26,000 --> 00:07:26,000
+tyre.
+
+87
+00:07:27,000 --> 00:07:34,000
+Let me know well there and it may result in additional latency, but is typically overcome by using
+
+88
+00:07:34,000 --> 00:07:35,000
+better middleware services.
+
+89
+00:07:36,000 --> 00:07:43,000
+That four connects directly to the database by converting GDP scores into database specific calls,
+
+90
+00:07:44,000 --> 00:07:53,000
+the B c type four driver, also known as a direct database Pure Java driver, is a database driver implementations
+
+91
+00:07:53,000 --> 00:08:00,000
+that converts basic calls directly into vendor specific database protocol written completely in Java
+
+92
+00:08:01,000 --> 00:08:08,000
+that for drivers as thus platform independent, they install inside the Java virtual machine of the
+
+93
+00:08:08,000 --> 00:08:09,000
+client.
+
+94
+00:08:09,000 --> 00:08:16,000
+This provides better performance isn't the type one and type two drivers, as it doesn't have the overhead
+
+95
+00:08:16,000 --> 00:08:21,000
+of conversion, of course, into B C O Database API calls.
+
+96
+00:08:22,000 --> 00:08:26,000
+Unlike the types three drivers, it doesn't need associated software to work.
+
+97
+00:08:27,000 --> 00:08:32,000
+Advantages are completely implemented in Java to achieve platform independence.
+
+98
+00:08:33,000 --> 00:08:41,000
+These drivers don't translate the requests into intermediary format, such as Odyssey Zygmunt application
+
+99
+00:08:41,000 --> 00:08:48,000
+connects directly to the database server, no translation or middleware layers I use, including performance.
+
+100
+00:08:49,000 --> 00:08:54,000
+The man can manage all aspects of the application to database connection.
+
+101
+00:08:54,000 --> 00:09:01,000
+This can facilitate debugging, and regarding these advantages, we must add that drivers database specific
+
+102
+00:09:02,000 --> 00:09:09,000
+has different database vendors to use widely different and usually proprietary network protocols.
+
+103
+00:09:09,000 --> 00:09:13,000
+But I believe this is not a critical disadvantage, considering all advantages.
+
+104
+00:09:14,000 --> 00:09:20,000
+Also, nowadays, all major databases have their own implementation of GitLab, and the only things
+
+105
+00:09:20,000 --> 00:09:26,000
+that you need to do is to add the basic driver into the class of your Java app.
+
+106
+00:09:27,000 --> 00:09:30,000
+So now, you know, different types of GBC driver.
+
+107
+00:09:31,000 --> 00:09:36,000
+Probably you already understood that we are going to learn how to work was GBC type four?
+
+108
+00:09:36,000 --> 00:09:39,000
+Let's recap one more time how it works.
+
+109
+00:09:39,000 --> 00:09:41,000
+We are going to have program code.
+
+110
+00:09:42,000 --> 00:09:44,000
+This can be any problem codes.
+
+111
+00:09:44,000 --> 00:09:52,000
+It performs operations with persistent storage in my course, Java from zero to the first job we create
+
+112
+00:09:52,000 --> 00:09:54,000
+online shop and the margins.
+
+113
+00:09:54,000 --> 00:10:01,000
+And during the user registration, we ran some codes that should store user before learning databases,
+
+114
+00:10:01,000 --> 00:10:03,000
+we store its users and file.
+
+115
+00:10:03,000 --> 00:10:10,000
+Now that code will interact with GDC API using standard interfaces.
+
+116
+00:10:10,000 --> 00:10:18,000
+GBC API will use implementation of the API, namely GBC driver for specific database management system
+
+117
+00:10:19,000 --> 00:10:24,000
+and Z Driver will set com Monsters database management system to execute sequel queries.
+
+118
+00:10:25,000 --> 00:10:28,000
+Here in the slides, you can see how it works.
+
+119
+00:10:29,000 --> 00:10:36,000
+Let's now have a lot of them, and I will show you how to add the busy driver to your app and establish
+
+120
+00:10:36,000 --> 00:10:37,000
+connection with the database.
+
+121
+00:10:38,000 --> 00:10:44,000
+In this lesson, we are going to do everything from configuration side to be sure that our development
+
+122
+00:10:44,000 --> 00:10:47,000
+environment is all set for the following lessons.
+
+123
+00:10:47,000 --> 00:10:54,000
+The first thing that we have to do is to get busy drivers that we need help to understand what driver
+
+124
+00:10:54,000 --> 00:10:57,000
+we need and where to download it very easily.
+
+125
+00:10:58,000 --> 00:11:01,000
+Just open your browser and make a Google search.
+
+126
+00:11:01,000 --> 00:11:04,000
+You have to type Mavin the wrapper for us.
+
+127
+00:11:04,000 --> 00:11:06,000
+This is a repository is a source.
+
+128
+00:11:06,000 --> 00:11:10,000
+A lot of artifacts libraries for Java development.
+
+129
+00:11:10,000 --> 00:11:15,000
+After that puts the name of your database management system and writes GBC.
+
+130
+00:11:16,000 --> 00:11:21,000
+Google search will show you page that should leave you to name a repository.
+
+131
+00:11:21,000 --> 00:11:24,000
+In our case, we have my school installed.
+
+132
+00:11:24,000 --> 00:11:27,000
+That's why I select my school connector.
+
+133
+00:11:28,000 --> 00:11:34,000
+Depending on the version of database management systems that you installed on your computer, you have
+
+134
+00:11:34,000 --> 00:11:36,000
+to select driver of the same version.
+
+135
+00:11:36,000 --> 00:11:40,000
+It will be enough to know at least major version now.
+
+136
+00:11:40,000 --> 00:11:43,000
+Case you installed my sequel of version eight.
+
+137
+00:11:44,000 --> 00:11:51,000
+That's why I select Here's the latest version available, and here we can download Java, then load
+
+138
+00:11:51,000 --> 00:11:52,000
+it on your PC.
+
+139
+00:11:53,000 --> 00:12:01,000
+Once, to the knowledge, we have to add that into the ClassPass of your project in I.D. In our case,
+
+140
+00:12:01,000 --> 00:12:02,000
+we are going to use Eclipse.
+
+141
+00:12:03,000 --> 00:12:09,000
+Let me quickly show you how to that external John to ClassPass in Eclipse Mouse.
+
+142
+00:12:09,000 --> 00:12:16,000
+Click on your project after that select Built Boss and after that, click on Configure Builds Pass Select
+
+143
+00:12:16,000 --> 00:12:17,000
+Libraries tab.
+
+144
+00:12:18,000 --> 00:12:20,000
+Click on ClassPass Boss.
+
+145
+00:12:20,000 --> 00:12:23,000
+And after that, click on Add External Jar.
+
+146
+00:12:23,000 --> 00:12:26,000
+After we can click Apply Close.
+
+147
+00:12:27,000 --> 00:12:27,000
+Great.
+
+148
+00:12:28,000 --> 00:12:35,000
+Now we have my sequel GBC Driver in our class boss, and we are ready to proceed with writing the code
+
+149
+00:12:35,000 --> 00:12:37,000
+to establish connection with our database.
+
+150
+00:12:38,000 --> 00:12:44,000
+All examples related to GDC will be stored in the separate package that is called GDC.
+
+151
+00:12:45,000 --> 00:12:51,000
+You can find the reference to the court examples that I'm going to show you in this lesson in attachments
+
+152
+00:12:51,000 --> 00:12:52,000
+to the lesson.
+
+153
+00:12:53,000 --> 00:12:55,000
+And now we are going through U.
+
+154
+00:12:55,000 --> 00:12:59,000
+S. Connection example file in this file, we have made massive.
+
+155
+00:13:00,000 --> 00:13:01,000
+And we can run it.
+
+156
+00:13:01,000 --> 00:13:05,000
+Let me go line by line to explain what we have here.
+
+157
+00:13:06,000 --> 00:13:13,000
+If you try to find tutorial in the internet about establishing connection with the database, most likely
+
+158
+00:13:13,000 --> 00:13:20,000
+you will find a lot of tutorials, whereas the first step is uploading driver loss into class boss in
+
+159
+00:13:20,000 --> 00:13:23,000
+a modern environment and in our environments setup.
+
+160
+00:13:24,000 --> 00:13:31,000
+This is not needed since all UBC drivers at the fountains across ClassPass automatically loaded, but
+
+161
+00:13:31,000 --> 00:13:38,000
+just in case I leave comments lines of code that demonstrates how to upload a class into a G.M..
+
+162
+00:13:39,000 --> 00:13:40,000
+Why is this is needed?
+
+163
+00:13:40,000 --> 00:13:49,000
+I mean, the lower driver class when you load driver class like this, or it is loaded into G.M. automatically,
+
+164
+00:13:49,000 --> 00:13:53,000
+according to general rules, static initialization is executed.
+
+165
+00:13:54,000 --> 00:14:00,000
+So let's open driver clusters code and investigate what is in the aesthetic consideration.
+
+166
+00:14:00,000 --> 00:14:05,000
+Love my school connector has open source code available on the top.
+
+167
+00:14:06,000 --> 00:14:11,000
+And here's how a driver class looks like you can find steady consolidation.
+
+168
+00:14:11,000 --> 00:14:17,000
+Look here where driver manager is used to register instance of the current driver.
+
+169
+00:14:18,000 --> 00:14:20,000
+That's why it is enough.
+
+170
+00:14:20,000 --> 00:14:26,000
+This class just to be loaded into the gym to perform all necessary configurations.
+
+171
+00:14:27,000 --> 00:14:34,000
+But as I said in our case, Joe will identify a driver in the class bus automatically and will load
+
+172
+00:14:34,000 --> 00:14:42,000
+driver class driver manager is one out of many classes from Java School Package that will use basically
+
+173
+00:14:42,000 --> 00:14:45,000
+Angeliki all classes related to school.
+
+174
+00:14:45,000 --> 00:14:52,000
+A group into Java School Package Driver Manager is a clause that is responsible for managing GBC.
+
+175
+00:14:52,000 --> 00:14:57,000
+Drivers also will use this class to create objects of connection type.
+
+176
+00:14:57,000 --> 00:15:00,000
+This will be used to execute SQL statements.
+
+177
+00:15:00,000 --> 00:15:06,000
+Once we are sure that driver is uploaded into the JVM, we need to establish connection.
+
+178
+00:15:07,000 --> 00:15:14,000
+Similar to other resources, we need to make sure that all resources are properly closed after they
+
+179
+00:15:14,000 --> 00:15:15,000
+were used.
+
+180
+00:15:16,000 --> 00:15:19,000
+That's why we use drivers resources below.
+
+181
+00:15:19,000 --> 00:15:25,000
+If you're not familiar with this blog, review the details in my complete Java course.
+
+182
+00:15:25,000 --> 00:15:33,000
+In the input output stream, top insured resources declared in Trailers Resources blog will be automatically
+
+183
+00:15:33,000 --> 00:15:36,000
+closed after the blog will be completely executed.
+
+184
+00:15:37,000 --> 00:15:42,000
+Java guarantees this and responsible for proper closure of their sources.
+
+185
+00:15:43,000 --> 00:15:49,000
+You can put on this blog only Typekit that implements articles about interface.
+
+186
+00:15:50,000 --> 00:15:56,000
+We use drama manager to get connection object, get connection mass, it is overloaded and we can use
+
+187
+00:15:56,000 --> 00:15:58,000
+different versions of it.
+
+188
+00:15:59,000 --> 00:16:00,000
+But there is the same.
+
+189
+00:16:01,000 --> 00:16:06,000
+You have to pass host of your SQL server where that the base is located and credentials.
+
+190
+00:16:07,000 --> 00:16:13,000
+You can see that overloaded masses might take is a string, and properties and brokerages says this
+
+191
+00:16:13,000 --> 00:16:16,000
+case will contain information about user and passwords.
+
+192
+00:16:17,000 --> 00:16:18,000
+Or you can pass one concatenate.
+
+193
+00:16:18,000 --> 00:16:23,000
+A string was all acquired information on three separate suites.
+
+194
+00:16:23,000 --> 00:16:25,000
+In our case, we pass three strings.
+
+195
+00:16:26,000 --> 00:16:28,000
+Let's look at what actually would pass here.
+
+196
+00:16:29,000 --> 00:16:33,000
+We concatenate hostname and database name as a first message argument.
+
+197
+00:16:34,000 --> 00:16:36,000
+After that, we pass user and password.
+
+198
+00:16:37,000 --> 00:16:43,000
+Definitely storing database credentials in the source code file is not the best practice, but for demo
+
+199
+00:16:43,000 --> 00:16:46,000
+purposes and for first, the basic program.
+
+200
+00:16:46,000 --> 00:16:48,000
+I believe for this, OK?
+
+201
+00:16:48,000 --> 00:16:54,000
+Later, when we will keep implementing our online store, I will show you where to put credentials.
+
+202
+00:16:55,000 --> 00:17:01,000
+Database name is the one that we created together in the last database.
+
+203
+00:17:01,000 --> 00:17:08,000
+If you remember, we created a database for our online store project here just to use its name.
+
+204
+00:17:09,000 --> 00:17:14,000
+Name of the schema, user and passwords is pretty clear and simple.
+
+205
+00:17:14,000 --> 00:17:22,000
+But let's look at the host name and understand how it looks like it contains that prefix and actually
+
+206
+00:17:22,000 --> 00:17:23,000
+is a euro.
+
+207
+00:17:23,000 --> 00:17:26,000
+This a host where our SQL server is running.
+
+208
+00:17:27,000 --> 00:17:31,000
+In our case, this is localhost and default port.
+
+209
+00:17:32,000 --> 00:17:35,000
+But how did they define which graphics to use?
+
+210
+00:17:35,000 --> 00:17:39,000
+Because it's a little bit different for connection with different database management systems.
+
+211
+00:17:39,000 --> 00:17:44,000
+This year, around establishes a database connection was a Java embedded driver.
+
+212
+00:17:45,000 --> 00:17:53,000
+The Java DB also includes and that's where Client Driver, which uses a different URL typically in the
+
+213
+00:17:53,000 --> 00:17:53,000
+database you.
+
+214
+00:17:54,000 --> 00:18:02,000
+You use the B c word column and database management system name, for example, to create the URL to
+
+215
+00:18:02,000 --> 00:18:04,000
+establish connection with their database.
+
+216
+00:18:05,000 --> 00:18:08,000
+You would write GBC Derbyshire for possibly a.
+
+217
+00:18:09,000 --> 00:18:15,000
+You will use PostgreSQL words here, and we establish in connection to my SQL that the best measurement
+
+218
+00:18:15,000 --> 00:18:16,000
+system.
+
+219
+00:18:16,000 --> 00:18:18,000
+That's why I have my sequel here.
+
+220
+00:18:19,000 --> 00:18:19,000
+Do you understand?
+
+221
+00:18:20,000 --> 00:18:26,000
+Anyway, you can always check this kind of detail in the documentation or by simply searching the internet.
+
+222
+00:18:27,000 --> 00:18:29,000
+The main part and that should be followed here.
+
+223
+00:18:29,000 --> 00:18:33,000
+I describe after we called get a connection method.
+
+224
+00:18:34,000 --> 00:18:36,000
+The connection variable should be initialized.
+
+225
+00:18:37,000 --> 00:18:41,000
+If for some reason it is now, that means connection wasn't that thing.
+
+226
+00:18:42,000 --> 00:18:48,000
+If it is not now, then let's congratulate ourselves with successfully established connection.
+
+227
+00:18:49,000 --> 00:18:55,000
+Let's run our application and we can see that connection established successfully.
+
+228
+00:18:56,000 --> 00:18:59,000
+Your connection may throw a sequel exception.
+
+229
+00:18:59,000 --> 00:19:04,000
+It may be thrown if a database access error occurs was a URL.
+
+230
+00:19:04,000 --> 00:19:10,000
+Is now also a child exception, maybe strong that is sequel to Mount Exception.
+
+231
+00:19:11,000 --> 00:19:17,000
+It may be thrown when the driver has determined that the timeout specified by the set logging timeout
+
+232
+00:19:17,000 --> 00:19:24,000
+method has been ICSI and has at least tried to cancel the current database connection at them.
+
+233
+00:19:25,000 --> 00:19:28,000
+That's why I handle potential SQL exception here.
+
+234
+00:19:29,000 --> 00:19:33,000
+That's it, and you can see that connection is successfully established.
+
+235
+00:19:33,000 --> 00:19:34,000
+Congrats.
+
+236
+00:19:35,000 --> 00:19:38,000
+That's all what I plans to cover in this lesson.
+
+237
+00:19:38,000 --> 00:19:40,000
+Let's recap what we have learned today.
+
+238
+00:19:41,000 --> 00:19:49,000
+In this lesson, we hold GDC overview and learn what is the B C s Valorant different GBC driver types?
+
+239
+00:19:50,000 --> 00:19:51,000
+I explained you.
+
+240
+00:19:51,000 --> 00:19:55,000
+What are the B c es after this lesson?
+
+241
+00:19:55,000 --> 00:19:57,000
+I believe you have understanding how do the do works?
+
+242
+00:19:58,000 --> 00:20:06,000
+And in real life example, I showed you how to add GBC driver into a Java project and establish connection
+
+243
+00:20:06,000 --> 00:20:08,000
+from your Java program with a database.
+
+244
+00:20:08,000 --> 00:20:11,000
+Now we are ready for the next lesson.
+
+245
+00:20:12,000 --> 00:20:13,000
+That's it for this lesson.
+
+246
+00:20:14,000 --> 00:20:15,000
+Thanks a lot for your attention.
+
+247
+00:20:15,000 --> 00:20:18,000
+Have a great day and see you in the next lesson.
+

52 - JDBC/001 Source-code-example-from-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc

52 - JDBC/002 Source-code-example-from-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc

52 - JDBC/002 Statement, PreparedStatement & CallableStatement_en.srt

@@ -0,0 +1,1076 @@
+1
+00:00:06,000 --> 00:00:12,000
+Hello again in this lesson, we keep learning GDC, and today we will learn how to execute cycle statements
+
+2
+00:00:12,000 --> 00:00:20,000
+from our application and how we can pass results from the database to process this data further inside
+
+3
+00:00:20,000 --> 00:00:21,000
+our program.
+
+4
+00:00:22,000 --> 00:00:25,000
+We'll start from learn of what statement is.
+
+5
+00:00:25,000 --> 00:00:31,000
+I will show you main message that will help you to execute school queries against anatomies.
+
+6
+00:00:32,000 --> 00:00:36,000
+These mascots are execute, execute, query and execute updates.
+
+7
+00:00:37,000 --> 00:00:40,000
+We're going to review different examples with these masses.
+
+8
+00:00:41,000 --> 00:00:46,000
+Also, I'm going to show you how to read results through chance films that need me with the help of
+
+9
+00:00:46,000 --> 00:00:51,000
+results set and in order, you could read data from results in the proper format.
+
+10
+00:00:51,000 --> 00:00:56,000
+We're going to the mapping between SQL data types and Java data types.
+
+11
+00:00:57,000 --> 00:01:02,000
+After that, I will explain what school injections are and how we can avoid them.
+
+12
+00:01:02,000 --> 00:01:05,000
+With the help of the prepared statement and the answers.
+
+13
+00:01:05,000 --> 00:01:10,000
+The lesson will learn how to invoke stored procedures and what callable statement is.
+
+14
+00:01:11,000 --> 00:01:14,000
+Today we're going to have practical lesson was a lot of examples.
+
+15
+00:01:15,000 --> 00:01:19,000
+So let me start with screen sharing and some code examples.
+
+16
+00:01:20,000 --> 00:01:26,000
+And the first thing that I'd like to start with is executing statements against database from our Java
+
+17
+00:01:26,000 --> 00:01:26,000
+program.
+
+18
+00:01:27,000 --> 00:01:33,000
+In the previous lessons learned how to establish connection to database we GDC driver.
+
+19
+00:01:33,000 --> 00:01:37,000
+Make sure you watch the previous lesson because this is important.
+
+20
+00:01:37,000 --> 00:01:44,000
+And before we learn statement plus and how to work with it, we need to do small refactoring in our
+
+21
+00:01:44,000 --> 00:01:47,000
+code to make sure we are efficient.
+
+22
+00:01:47,000 --> 00:01:53,000
+In the following examples you saw in previous lesson how to get the connection object and take into
+
+23
+00:01:53,000 --> 00:01:54,000
+account.
+
+24
+00:01:54,000 --> 00:01:57,000
+We would need connection, object and a lot of times.
+
+25
+00:01:57,000 --> 00:01:59,000
+Basically, in each our example.
+
+26
+00:02:00,000 --> 00:02:05,000
+That's why it is a good idea to which repeatable code and move it into one plus.
+
+27
+00:02:06,000 --> 00:02:14,000
+Here I have class this code DB utils in a static method get connection that creates objects of connection
+
+28
+00:02:14,000 --> 00:02:17,000
+time and returns as a reference to the object.
+
+29
+00:02:18,000 --> 00:02:25,000
+Having this Glosson, this method would save my time by not writing all this code all the times, including
+
+30
+00:02:25,000 --> 00:02:26,000
+exception handling.
+
+31
+00:02:27,000 --> 00:02:28,000
+Does it make sense?
+
+32
+00:02:28,000 --> 00:02:32,000
+And now let's learn how to work with statement loss.
+
+33
+00:02:32,000 --> 00:02:38,000
+Let me open another example file is called GDC statement select example.
+
+34
+00:02:39,000 --> 00:02:43,000
+We have made massive here that will allow us to start the program.
+
+35
+00:02:44,000 --> 00:02:49,000
+So let's start from review of this massive I connection.
+
+36
+00:02:50,000 --> 00:02:55,000
+After that, I create statement object based on my connection object.
+
+37
+00:02:55,000 --> 00:02:59,000
+I just co-create statement without any parameters.
+
+38
+00:02:59,000 --> 00:03:06,000
+Statement object is used for an aesthetic SQL statement and the returns results it produces.
+
+39
+00:03:07,000 --> 00:03:14,000
+In previous lesson, we learned that we should close connection object the same sync we have to do with
+
+40
+00:03:14,000 --> 00:03:15,000
+statement object.
+
+41
+00:03:15,000 --> 00:03:22,000
+It is a good practice to close statements, to statement time extents at a plausible interface.
+
+42
+00:03:22,000 --> 00:03:25,000
+That's why we can also put it in.
+
+43
+00:03:25,000 --> 00:03:26,000
+The try was resources block.
+
+44
+00:03:27,000 --> 00:03:33,000
+And here is where knowledge of sequel will come in handy because you need to have equal knowledge to
+
+45
+00:03:33,000 --> 00:03:35,000
+create SQL statements.
+
+46
+00:03:35,000 --> 00:03:37,000
+This will be used in statements object.
+
+47
+00:03:38,000 --> 00:03:43,000
+Let's create cyclase select statements of neutrons as all users from user table.
+
+48
+00:03:43,000 --> 00:03:51,000
+If you missed lessons about database or you just figured out our tables look like I will quickly remind
+
+49
+00:03:51,000 --> 00:03:58,000
+you, we created database where we also created tables that will represent our business in our applications
+
+50
+00:03:58,000 --> 00:04:01,000
+that we develop in our online store.
+
+51
+00:04:02,000 --> 00:04:07,000
+And one of such tables is user table that contains information about our users.
+
+52
+00:04:07,000 --> 00:04:12,000
+And here's how it looks like let's fetch information from this table.
+
+53
+00:04:13,000 --> 00:04:18,000
+This seamless query to fetch all data is select all from user.
+
+54
+00:04:19,000 --> 00:04:21,000
+Let's get back to our general application now.
+
+55
+00:04:22,000 --> 00:04:29,000
+Now, we're sea to talk about Statement Object has three main assets to work with.
+
+56
+00:04:30,000 --> 00:04:38,000
+All of them executed SQL statement against database zero execute, execute, query and execute update.
+
+57
+00:04:39,000 --> 00:04:42,000
+Let's find out what is the difference between these methods.
+
+58
+00:04:42,000 --> 00:04:48,000
+All these massive stakes drink massive argument is that a sequel query that we are going to execute?
+
+59
+00:04:49,000 --> 00:04:55,000
+The main difference is in the return values, for example, execute mass returns.
+
+60
+00:04:55,000 --> 00:04:57,000
+Boolean value true is return.
+
+61
+00:04:57,000 --> 00:05:05,000
+If return type is a result, set object and forces return when returns value is an ability to count
+
+62
+00:05:05,000 --> 00:05:06,000
+closer and the results.
+
+63
+00:05:07,000 --> 00:05:13,000
+They remember that when we execute a sequel statements in my school workbench, for example, and we
+
+64
+00:05:13,000 --> 00:05:21,000
+execute that update query or insert query we saw in looks number of rows in proxies was query, and
+
+65
+00:05:21,000 --> 00:05:25,000
+then keys will receive no execute mass that will return false.
+
+66
+00:05:26,000 --> 00:05:31,000
+But when we executed select statement in database, we received table was values.
+
+67
+00:05:31,000 --> 00:05:36,000
+This is called the results set and includes results set is returned.
+
+68
+00:05:36,000 --> 00:05:38,000
+We received two in this message.
+
+69
+00:05:39,000 --> 00:05:45,000
+Technically speaking, you can execute all kinds of queries via execute mass, but execution of select
+
+70
+00:05:45,000 --> 00:05:47,000
+statements totally makes no sense.
+
+71
+00:05:47,000 --> 00:05:55,000
+We execute massive understand why, and also, it is not a lot of sense in execution of queries.
+
+72
+00:05:55,000 --> 00:05:58,000
+If you want to see count of rows in part, that was sequel query.
+
+73
+00:05:59,000 --> 00:06:05,000
+Probably the only case when you might want to use execute method use case when you execute dynamically.
+
+74
+00:06:05,000 --> 00:06:10,000
+Unknown SQL statement If you want to get results, set objects in response.
+
+75
+00:06:11,000 --> 00:06:20,000
+We need to use, execute, query, mass, execute, query mass returns results set as you already understand
+
+76
+00:06:20,000 --> 00:06:26,000
+object of results that will allow you to read all rows as it was returned by database.
+
+77
+00:06:26,000 --> 00:06:31,000
+Line by line and execute these massive returns in value.
+
+78
+00:06:32,000 --> 00:06:35,000
+Nobody understands what is this value?
+
+79
+00:06:35,000 --> 00:06:40,000
+Is it a zero count that was impacted by school statement?
+
+80
+00:06:40,000 --> 00:06:45,000
+Basically, we can receive the same number here in Java program.
+
+81
+00:06:45,000 --> 00:06:51,000
+For example, insert, update or delete statements, which is a number of rows.
+
+82
+00:06:51,000 --> 00:06:53,000
+In fact, it was a query execution.
+
+83
+00:06:53,000 --> 00:07:00,000
+So this massive is not suitable for select statements because again, when we execute select statements,
+
+84
+00:07:01,000 --> 00:07:03,000
+we count on receiving some detailed response.
+
+85
+00:07:04,000 --> 00:07:10,000
+That's why so radically it makes sense to execute, insert, update or delete queries.
+
+86
+00:07:10,000 --> 00:07:11,000
+Execute, update mass.
+
+87
+00:07:12,000 --> 00:07:19,000
+So then the now is the difference between these three masses and what message do we need to use?
+
+88
+00:07:19,000 --> 00:07:21,000
+And then a select statement example.
+
+89
+00:07:21,000 --> 00:07:22,000
+You are right.
+
+90
+00:07:22,000 --> 00:07:24,000
+We need to use, execute, query mass.
+
+91
+00:07:25,000 --> 00:07:27,000
+Let's get back to our demo file.
+
+92
+00:07:28,000 --> 00:07:31,000
+Now, let's talk a little bit more about results set.
+
+93
+00:07:33,000 --> 00:07:41,000
+Results set is a table of data representing that the least result set, this subject maintains a cursor
+
+94
+00:07:41,000 --> 00:07:44,000
+pointing to its current row of data.
+
+95
+00:07:44,000 --> 00:07:49,000
+Initially, the cursor is positioned before the first row.
+
+96
+00:07:49,000 --> 00:07:53,000
+The next massive move the cursor does the next row.
+
+97
+00:07:54,000 --> 00:08:00,000
+Next, mass protests force one zero and no more rows as a result set object.
+
+98
+00:08:00,000 --> 00:08:09,000
+That's why this massive can be used in whilo to iterate over all the rows in results set by default.
+
+99
+00:08:09,000 --> 00:08:15,000
+Only one result said object per statement object can be opened at the same time.
+
+100
+00:08:15,000 --> 00:08:22,000
+Therefore, if the reading of one result set object is interleaved with the reading of the.
+
+101
+00:08:23,000 --> 00:08:29,000
+Each must have been generated by different statement objects, all execution mass.
+
+102
+00:08:29,000 --> 00:08:35,000
+In the statement, the interface implies a close occurrence results at object of the statement.
+
+103
+00:08:35,000 --> 00:08:42,000
+If an open one exists, but nevertheless close enough results, Seth is considered to be a good practice.
+
+104
+00:08:43,000 --> 00:08:45,000
+That's why I put results set in.
+
+105
+00:08:45,000 --> 00:08:53,000
+Try was resources block here, and when we have results set, we can iterate over each row going one
+
+106
+00:08:53,000 --> 00:08:54,000
+by one.
+
+107
+00:08:55,000 --> 00:09:03,000
+I create while loop here and call next mass to move on that there's a next throw and to make sure that
+
+108
+00:09:03,000 --> 00:09:06,000
+the next rule exists in the results set.
+
+109
+00:09:06,000 --> 00:09:15,000
+After that, I can extract values from as a result, said Roe, was get less interested in seeing that
+
+110
+00:09:15,000 --> 00:09:22,000
+you can extract the values of this already in Java, the time there is a map in between sequel data
+
+111
+00:09:22,000 --> 00:09:24,000
+types and Java data types.
+
+112
+00:09:24,000 --> 00:09:25,000
+Let's review.
+
+113
+00:09:27,000 --> 00:09:32,000
+On this slide, you can see mapping between data types that are familiar to you from database management
+
+114
+00:09:32,000 --> 00:09:34,000
+system and from Java.
+
+115
+00:09:35,000 --> 00:09:43,000
+For example, if fields in database is a virtual data type, that means that you can put it in stream
+
+116
+00:09:43,000 --> 00:09:44,000
+data that.
+
+117
+00:09:45,000 --> 00:09:55,000
+If there is a tiny in data type that is equivalent of integer in Java, it makes sense and results that
+
+118
+00:09:55,000 --> 00:09:59,000
+has masses that allow you to extract value of specific data time.
+
+119
+00:10:00,000 --> 00:10:01,000
+Let's get back to our demo.
+
+120
+00:10:03,000 --> 00:10:10,000
+And Nine's data times that you want to extract, you have to promise mess that answers that all matters
+
+121
+00:10:10,000 --> 00:10:19,000
+are overloaded they can take is an argument those three arguments and value will indicate in the course
+
+122
+00:10:19,000 --> 00:10:27,000
+of a column, considering that order of columns may be changed and new columns may be added.
+
+123
+00:10:27,000 --> 00:10:30,000
+This is not something we can always rely on.
+
+124
+00:10:30,000 --> 00:10:37,000
+That's why it is recommended to extract value from column by column name, and you can seize it.
+
+125
+00:10:37,000 --> 00:10:43,000
+I pass column Nathan slabs of values that I need that tensions.
+
+126
+00:10:43,000 --> 00:10:48,000
+This is exactly the name of a column like it is named in the database.
+
+127
+00:10:49,000 --> 00:10:55,000
+I extract the first name, last name and email for each user.
+
+128
+00:10:56,000 --> 00:10:59,000
+Let's run this program and see what we have.
+
+129
+00:10:59,000 --> 00:11:00,000
+And so.
+
+130
+00:11:00,000 --> 00:11:04,000
+And as you can see, we printed information about each user.
+
+131
+00:11:05,000 --> 00:11:08,000
+They understand how we can execute select statements.
+
+132
+00:11:09,000 --> 00:11:11,000
+Muscles super complex agreed.
+
+133
+00:11:12,000 --> 00:11:19,000
+Now, let me show you obvious example, this example has a lot of in common with the previous one.
+
+134
+00:11:20,000 --> 00:11:22,000
+Let's focus on the sea.
+
+135
+00:11:22,000 --> 00:11:23,000
+Is it a different?
+
+136
+00:11:24,000 --> 00:11:26,000
+We have different SQL statements here.
+
+137
+00:11:27,000 --> 00:11:35,000
+This storm, we are going to update the amount of money for User ID 17 and instead of executed query,
+
+138
+00:11:36,000 --> 00:11:38,000
+I call execute update massive.
+
+139
+00:11:39,000 --> 00:11:42,000
+And after that, I agreed to consult amount of rules.
+
+140
+00:11:42,000 --> 00:11:44,000
+Is it the impact that the possibility of wearing?
+
+141
+00:11:45,000 --> 00:11:52,000
+I believe you already understood how this thinks about all the examples from this lesson will be in
+
+142
+00:11:52,000 --> 00:11:53,000
+attachments.
+
+143
+00:11:53,000 --> 00:11:54,000
+There's a lesson.
+
+144
+00:11:54,000 --> 00:11:57,000
+So feel free to investigate this by yourself.
+
+145
+00:11:58,000 --> 00:12:02,000
+You can find those examples was delete and insert statements.
+
+146
+00:12:03,000 --> 00:12:09,000
+I believe that we are more or less clear on how statements are less than prepared statements now.
+
+147
+00:12:10,000 --> 00:12:12,000
+But before the then prepared statements.
+
+148
+00:12:12,000 --> 00:12:18,000
+Let me show you one of the problems that we have learned to solve with the help of prepared statements.
+
+149
+00:12:20,000 --> 00:12:28,000
+One of the malicious attacks in Web applications are sequel injections, sequel injection is a web security
+
+150
+00:12:28,000 --> 00:12:37,000
+vulnerability that allows and target the interfere was Aquaris Z and application makes its database.
+
+151
+00:12:38,000 --> 00:12:44,000
+It generally allows in a pocket to view data that they're not normally able to retrieve.
+
+152
+00:12:44,000 --> 00:12:52,000
+This might include data belonging to Aussie users or any other data as its application self is able
+
+153
+00:12:52,000 --> 00:13:01,000
+to access in many cases, and Typekit can modify as data, causing persistent changes to the applications,
+
+154
+00:13:01,000 --> 00:13:02,000
+content or behaviour.
+
+155
+00:13:03,000 --> 00:13:07,000
+For example, I talked to my query passwords of users.
+
+156
+00:13:07,000 --> 00:13:15,000
+I'll get Aussies sensitive data, zao wide variety of SQL injection vulnerabilities, attacks and techniques
+
+157
+00:13:16,000 --> 00:13:18,000
+which arise in different situations.
+
+158
+00:13:18,000 --> 00:13:26,000
+Some common SQL injection examples include retrieving hidden data where you can modify and SQL query
+
+159
+00:13:26,000 --> 00:13:28,000
+through June additional results.
+
+160
+00:13:29,000 --> 00:13:38,000
+Subverting application logic where you can change a query to interfere with the applications logic union
+
+161
+00:13:38,000 --> 00:13:44,000
+attacks, where you can retrieve data from different that the base tables next to mine is the database
+
+162
+00:13:45,000 --> 00:13:50,000
+where you can extract information about the version and structure of the database.
+
+163
+00:13:51,000 --> 00:13:58,000
+Blind SQL injection was the results of the query control and not returns in the applications responses.
+
+164
+00:13:59,000 --> 00:14:07,000
+Let's imagine now that we have online shop and we pass category name as URL parameter like it is shown
+
+165
+00:14:07,000 --> 00:14:08,000
+on this slide.
+
+166
+00:14:08,000 --> 00:14:17,000
+And imagine that the category parameter is used in our statement in Java code, namely would take value
+
+167
+00:14:17,000 --> 00:14:22,000
+of category parameter and use it to concatenate our SQL statement.
+
+168
+00:14:23,000 --> 00:14:30,000
+This request triggers squaring where I extract all products from category computers, for example,
+
+169
+00:14:30,000 --> 00:14:32,000
+and status status:active.
+
+170
+00:14:33,000 --> 00:14:40,000
+Probably you're seeing what might be wrong here, but what would happen if I would add double five cents
+
+171
+00:14:40,000 --> 00:14:41,000
+in the URL?
+
+172
+00:14:42,000 --> 00:14:47,000
+This means that these double hyphens will be added to the sequel statement.
+
+173
+00:14:47,000 --> 00:14:53,000
+Double hyphens means commas in sequel syntax and amerson.
+
+174
+00:14:53,000 --> 00:14:56,000
+What will go after them will be treated as a commons.
+
+175
+00:14:57,000 --> 00:15:05,000
+Thus, you will extract all products in active and inactive status that understands us now or imagines
+
+176
+00:15:05,000 --> 00:15:08,000
+that the past category parameter was unknown.
+
+177
+00:15:08,000 --> 00:15:15,000
+Keyword and in union statement, you can pass another sequel statement to query the tables.
+
+178
+00:15:16,000 --> 00:15:23,000
+Thus, I talked to my extract information that he or she were not supposed to have access to.
+
+179
+00:15:23,000 --> 00:15:27,000
+Can you imagine now what potential impact might be?
+
+180
+00:15:28,000 --> 00:15:32,000
+That's why securing your app from SQL injections is so important.
+
+181
+00:15:33,000 --> 00:15:38,000
+And let's learn now how we can secure ourselves from SQL injections.
+
+182
+00:15:39,000 --> 00:15:41,000
+Now you know what SQL injection is.
+
+183
+00:15:41,000 --> 00:15:43,000
+Let's find out what we can do with that.
+
+184
+00:15:45,000 --> 00:15:52,000
+One of the ways to avoid SQL injections is to use prepared statement, because prepared statement defines
+
+185
+00:15:52,000 --> 00:16:00,000
+a single query template and lets client only define parameters, values you prepared statement and after
+
+186
+00:16:00,000 --> 00:16:08,000
+that, we only need to populate parameters in that suit by using parametric queries and prepared statement.
+
+187
+00:16:09,000 --> 00:16:17,000
+You prevent many forms of SQL injection because all the parameters passed as part of the placeholders
+
+188
+00:16:17,000 --> 00:16:20,000
+will be escaped automatically by the C driver.
+
+189
+00:16:21,000 --> 00:16:24,000
+But this is not the only advantage of prepared statement.
+
+190
+00:16:25,000 --> 00:16:28,000
+Also, prepared statements have better performance.
+
+191
+00:16:29,000 --> 00:16:36,000
+SQL queries post does a prepared statement Massive got a database for completion immediately.
+
+192
+00:16:36,000 --> 00:16:45,000
+We see drivers course if a dozen zent per compilation occurs when you executes prepared queries, press
+
+193
+00:16:45,000 --> 00:16:52,000
+statement queries operate compile tons of database and access plans will be used to execute further
+
+194
+00:16:52,000 --> 00:16:59,000
+queries, which allows them to execute much faster than normal queries generated by statement object.
+
+195
+00:17:00,000 --> 00:17:06,000
+You should always try to use prepared statement in the production of the B C code to reduce the load
+
+196
+00:17:06,000 --> 00:17:09,000
+on the database in order to get a performance benefit.
+
+197
+00:17:09,000 --> 00:17:17,000
+It is, of course, nothing to use only a parameterized version of SQL query and not with string impersonation.
+
+198
+00:17:18,000 --> 00:17:24,000
+And last but not least, advantage of prepared statement is obvious it allows you to create parameterized
+
+199
+00:17:24,000 --> 00:17:32,000
+SQL queries and sent different parameters by using the same SQL queries you can use question mark and
+
+200
+00:17:32,000 --> 00:17:36,000
+the query as a placeholder is substituted by any other value.
+
+201
+00:17:37,000 --> 00:17:39,000
+Enough CRM a prepared statement.
+
+202
+00:17:40,000 --> 00:17:41,000
+Let's look at examples.
+
+203
+00:17:42,000 --> 00:17:48,000
+I put all examples related to prepared statements in a separate package is that the squad prepared statements,
+
+204
+00:17:49,000 --> 00:17:56,000
+basically, all queries here performs the same operation as an example with statement, but was only
+
+205
+00:17:56,000 --> 00:17:57,000
+one difference.
+
+206
+00:17:57,000 --> 00:18:01,000
+I use prepared statement type instead of statement.
+
+207
+00:18:01,000 --> 00:18:04,000
+Let's review insert example.
+
+208
+00:18:04,000 --> 00:18:11,000
+You can see that I have the same SQL statement as a previous example, but instead of values, I put
+
+209
+00:18:11,000 --> 00:18:13,000
+question marks here.
+
+210
+00:18:14,000 --> 00:18:16,000
+After that, I call prepared statement.
+
+211
+00:18:17,000 --> 00:18:22,000
+Massad gives the reference to the prepared statement object, and after that, I can.
+
+212
+00:18:22,000 --> 00:18:30,000
+Initialize each of these parameters was values I can set values of different types you can use as a
+
+213
+00:18:30,000 --> 00:18:35,000
+suggestion feature in your I.D. Then more info about available masses.
+
+214
+00:18:36,000 --> 00:18:38,000
+But all of them have intuitive meaning.
+
+215
+00:18:39,000 --> 00:18:43,000
+If you need to set string, just call sets three and massive.
+
+216
+00:18:44,000 --> 00:18:52,000
+If you need to set the integer, then need to invoke set end mass and so on that tensions of index number
+
+217
+00:18:52,000 --> 00:18:54,000
+one means the first position.
+
+218
+00:18:54,000 --> 00:18:55,000
+Of course not.
+
+219
+00:18:56,000 --> 00:19:00,000
+So we start not from zero, but from one.
+
+220
+00:19:00,000 --> 00:19:01,000
+Is it clear?
+
+221
+00:19:02,000 --> 00:19:05,000
+I'm here, I said values for each parameter.
+
+222
+00:19:06,000 --> 00:19:13,000
+And after that, I call execute update massive without any arguments and the queries executed.
+
+223
+00:19:14,000 --> 00:19:18,000
+Basically, that's how prepared statements were not complex complex.
+
+224
+00:19:20,000 --> 00:19:22,000
+I believe we had done was prepared statement.
+
+225
+00:19:23,000 --> 00:19:26,000
+And one more scene that I'd like to show you today.
+
+226
+00:19:26,000 --> 00:19:28,000
+It is callable statement.
+
+227
+00:19:28,000 --> 00:19:32,000
+The interface used to execute sequence stored procedures.
+
+228
+00:19:33,000 --> 00:19:39,000
+We learned in details what procedures are in our sequels section of the course.
+
+229
+00:19:40,000 --> 00:19:47,000
+That's why usually I started to see on the after students learned databases because without knowing
+
+230
+00:19:47,000 --> 00:19:53,000
+that, it is hard to understand such terms as stored procedures, for example.
+
+231
+00:19:54,000 --> 00:20:00,000
+Let me just quickly remind you what stored procedures are stored procedures, a group of statements
+
+232
+00:20:00,000 --> 00:20:07,000
+that we compile in the database for some past storage procedures, I've been official one.
+
+233
+00:20:07,000 --> 00:20:14,000
+We are dealing with multiple tables with complex scenario, and rather than sending multiple queries
+
+234
+00:20:14,000 --> 00:20:21,000
+to the database, we can send the required data to the storage procedure and have the logic executed
+
+235
+00:20:21,000 --> 00:20:23,000
+in the database server itself.
+
+236
+00:20:24,000 --> 00:20:31,000
+So to make sure you understand everything what I say, check Larsons databases.
+
+237
+00:20:31,000 --> 00:20:34,000
+In that course, we created stored procedures.
+
+238
+00:20:35,000 --> 00:20:37,000
+Let's not invoke one of them.
+
+239
+00:20:38,000 --> 00:20:46,000
+As usual, we create connection after that, and we'll prepare call massive IPOs SQL statement as it
+
+240
+00:20:46,000 --> 00:20:48,000
+should be my stored procedure.
+
+241
+00:20:49,000 --> 00:20:53,000
+Instead of that argument, I possibly hold it.
+
+242
+00:20:53,000 --> 00:21:01,000
+And after that, similar to a prepared statement, initialize argument with the value in specific position.
+
+243
+00:21:02,000 --> 00:21:09,000
+If you remember stored procedures, Zara might be different argument types in, out and in.
+
+244
+00:21:09,000 --> 00:21:16,000
+Now, in case you want to declare that one of the parameters is out parameter, you have to register
+
+245
+00:21:16,000 --> 00:21:16,000
+it first.
+
+246
+00:21:17,000 --> 00:21:19,000
+Like, here is a command line.
+
+247
+00:21:19,000 --> 00:21:22,000
+Argument index and argument time.
+
+248
+00:21:23,000 --> 00:21:30,000
+Pay attention that you should specify sequel type here, in my case, I have only one argument and it
+
+249
+00:21:30,000 --> 00:21:32,000
+is not out type argument.
+
+250
+00:21:33,000 --> 00:21:36,000
+That's why I keep this one command.
+
+251
+00:21:37,000 --> 00:21:39,000
+And after that, everything goes as usual.
+
+252
+00:21:40,000 --> 00:21:44,000
+We can call execute very massive returns as results set.
+
+253
+00:21:45,000 --> 00:21:52,000
+After that, we work with it, as in previous examples, in this particular case, my stored procedure
+
+254
+00:21:52,000 --> 00:22:00,000
+recount me user by email and in case you have out parameter and you want to read it, you can read it
+
+255
+00:22:00,000 --> 00:22:04,000
+from global statement object after you executed.
+
+256
+00:22:04,000 --> 00:22:06,000
+The query likens this example.
+
+257
+00:22:07,000 --> 00:22:11,000
+You read the Java times that you need to use and get masses.
+
+258
+00:22:12,000 --> 00:22:13,000
+Basically, that's it.
+
+259
+00:22:14,000 --> 00:22:17,000
+That's all what I wanted to learn with you in this lesson.
+
+260
+00:22:18,000 --> 00:22:21,000
+Let's recap what we have learned today.
+
+261
+00:22:22,000 --> 00:22:25,000
+They've announced a lot of things, and we had a lot of them.
+
+262
+00:22:26,000 --> 00:22:32,000
+Now you know what statement is and how to represent yourself, how to work with results, its object
+
+263
+00:22:33,000 --> 00:22:40,000
+when and mapping between cycle data types and Java data types in order to read data from results that
+
+264
+00:22:40,000 --> 00:22:40,000
+properly.
+
+265
+00:22:41,000 --> 00:22:49,000
+Now you know what SQL injection are and how it once was, how well prepared statement and at the end
+
+266
+00:22:49,000 --> 00:22:55,000
+of the lesson we learned with you callable statement, that's all what I wanted to share with you in
+
+267
+00:22:55,000 --> 00:22:56,000
+this lesson.
+
+268
+00:22:57,000 --> 00:22:58,000
+Thanks a lot for your attention.
+
+269
+00:22:58,000 --> 00:23:01,000
+Have a great day and see you in the next lesson.
+

52 - JDBC/003 Source-code-example-from-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc

52 - JDBC/003 Transactions, Batch Updates and MetaData_en.srt

@@ -0,0 +1,1060 @@
+1
+00:00:06,000 --> 00:00:06,000
+Hello yesterday.
+
+2
+00:00:07,000 --> 00:00:12,000
+I'm happy watching this lesson, because today we're going to have not very long but super important
+
+3
+00:00:12,000 --> 00:00:15,000
+lessons for advanced usage of GDC.
+
+4
+00:00:15,000 --> 00:00:20,000
+Today, we're going to talk about transactions and virtual dates, a database.
+
+5
+00:00:21,000 --> 00:00:24,000
+We'll start from understanding of what transactions are.
+
+6
+00:00:24,000 --> 00:00:29,000
+We'll learn Siri and such basic requirements to transactions as acid.
+
+7
+00:00:30,000 --> 00:00:35,000
+After Understand the Siri unreal example will create Java program that uses transactions.
+
+8
+00:00:36,000 --> 00:00:42,000
+I'll show you how we can commit our transactions roll back transaction in case of error or roll back
+
+9
+00:00:42,000 --> 00:00:44,000
+all that required safe point.
+
+10
+00:00:44,000 --> 00:00:50,000
+Also in this lesson, I'm going to show you how we can make batch updates to the database to increase
+
+11
+00:00:50,000 --> 00:00:51,000
+performance of our app.
+
+12
+00:00:52,000 --> 00:00:56,000
+And then comes the lesson we'll talk about how to explore this amazing method.
+
+13
+00:00:56,000 --> 00:00:57,000
+Need that programmatically?
+
+14
+00:00:57,000 --> 00:00:59,000
+Let's start our lesson.
+
+15
+00:00:59,000 --> 00:01:02,000
+And the first things that we are going to do in our lesson.
+
+16
+00:01:02,000 --> 00:01:06,000
+Let's define what transaction is in programming.
+
+17
+00:01:06,000 --> 00:01:12,000
+We refer to transaction as a group of related actions that need to be performed as a single action.
+
+18
+00:01:13,000 --> 00:01:20,000
+In other words, a transaction is a logical unit of work whose effect is visible outside the transaction,
+
+19
+00:01:20,000 --> 00:01:23,000
+either in its entirety or not at all.
+
+20
+00:01:23,000 --> 00:01:28,000
+We require this to ensure data integrity and now applications to understand it better.
+
+21
+00:01:29,000 --> 00:01:35,000
+Imagine simple examples if you went through multiple times, I hope this is checkout in online store.
+
+22
+00:01:36,000 --> 00:01:43,000
+You're on the checkout page and you are redirected to the payment gateway ZAPU actions that needed to
+
+23
+00:01:43,000 --> 00:01:43,000
+be done.
+
+24
+00:01:44,000 --> 00:01:50,000
+Let me even simplify things, and let's imagine that we have just three steps reducing money amount
+
+25
+00:01:50,000 --> 00:01:57,000
+on your credit card increasing mountains account of online store creation request for product delivery.
+
+26
+00:01:58,000 --> 00:02:01,000
+An exception might happen on each of these steps.
+
+27
+00:02:01,000 --> 00:02:07,000
+For example, you don't have enough money in your credit card or there is an exception in receiving
+
+28
+00:02:07,000 --> 00:02:09,000
+money on the side of online store.
+
+29
+00:02:09,000 --> 00:02:16,000
+Probably, they forgot to update accounts with relevant bank details or wild transaction has been happening.
+
+30
+00:02:16,000 --> 00:02:22,000
+Your product has been purchased by somebody else and requests for delivery can be created.
+
+31
+00:02:23,000 --> 00:02:29,000
+This is just an example because there might be different cases, and though it cases was missing products
+
+32
+00:02:29,000 --> 00:02:35,000
+for delivery, you can reserve the products for 15 minutes before checkout process has started.
+
+33
+00:02:35,000 --> 00:02:39,000
+But this thing implemented in different ways, in different cases.
+
+34
+00:02:39,000 --> 00:02:46,000
+The only things that I want you to pay attention to is that you may have multiple related steps where
+
+35
+00:02:46,000 --> 00:02:50,000
+we have value only successful completion of all steps.
+
+36
+00:02:50,000 --> 00:02:54,000
+And in the case, at least one of the steps is not completed.
+
+37
+00:02:55,000 --> 00:03:00,000
+We have to restore state of the system as it was before transactions started.
+
+38
+00:03:01,000 --> 00:03:08,000
+Basically, return money to your credit card or additional money from online store or reject requests
+
+39
+00:03:08,000 --> 00:03:09,000
+for product delivery.
+
+40
+00:03:09,000 --> 00:03:14,000
+Then now what transaction is and how it helps us to solve our business cases?
+
+41
+00:03:15,000 --> 00:03:16,000
+Great.
+
+42
+00:03:16,000 --> 00:03:22,000
+The next thing that we are going to learn is a set of properties of a transaction in time that a guaranteed
+
+43
+00:03:22,000 --> 00:03:28,000
+data validity despite errors, power failures and other mishaps.
+
+44
+00:03:28,000 --> 00:03:37,000
+This set of principles is called a set, this acronym that stands for authenticity, consistency, independence,
+
+45
+00:03:37,000 --> 00:03:38,000
+durability.
+
+46
+00:03:38,000 --> 00:03:45,000
+These four properties are the major guarantees of the transaction paradigm, which has influenced many
+
+47
+00:03:45,000 --> 00:03:48,000
+aspects of development in database systems.
+
+48
+00:03:49,000 --> 00:03:52,000
+And now we're going to learn each of these principles.
+
+49
+00:03:52,000 --> 00:03:55,000
+Let's start from the first one at Thomas.
+
+50
+00:03:56,000 --> 00:03:57,000
+What does a Thomas said to me?
+
+51
+00:03:58,000 --> 00:04:01,000
+Transactions are often composed of multiple statements.
+
+52
+00:04:02,000 --> 00:04:07,000
+Our Thomas ensures that all changes we make those a data as part of a transaction.
+
+53
+00:04:08,000 --> 00:04:10,000
+We manage them as a single entity and operation.
+
+54
+00:04:11,000 --> 00:04:18,000
+This effectively means is that the ease of perform, all the changes on none of that and atomic system
+
+55
+00:04:18,000 --> 00:04:26,000
+must guarantee, I promise it, in each and every situation, including power failures, errors and
+
+56
+00:04:26,000 --> 00:04:26,000
+crashes.
+
+57
+00:04:27,000 --> 00:04:30,000
+A guarantee of automaticity prevents updates.
+
+58
+00:04:30,000 --> 00:04:37,000
+That's a basic human only partially, which can cause greater problems than rejection is a whole series
+
+59
+00:04:37,000 --> 00:04:39,000
+outright as a consequence.
+
+60
+00:04:39,000 --> 00:04:46,000
+This transaction cannot be observed to be in progress by another database client at one moment in time.
+
+61
+00:04:46,000 --> 00:04:52,000
+It has not yet happened, and the next it has already occurred in the hall.
+
+62
+00:04:52,000 --> 00:04:53,000
+Almost none happened.
+
+63
+00:04:54,000 --> 00:04:56,000
+The transaction was cancelled in progress.
+
+64
+00:04:56,000 --> 00:05:02,000
+An example of an atomic transaction is monetary transfer from bank account a thorough account.
+
+65
+00:05:03,000 --> 00:05:10,000
+It consists of two operations withdrawing the money from a county and saving it that can be performing
+
+66
+00:05:10,000 --> 00:05:17,000
+these operations in an atomic transaction ensures that the database remains in a consistent state.
+
+67
+00:05:18,000 --> 00:05:19,000
+That is money.
+
+68
+00:05:19,000 --> 00:05:20,000
+Is this devoted?
+
+69
+00:05:20,000 --> 00:05:24,000
+No credited if either of those two operations fail.
+
+70
+00:05:25,000 --> 00:05:33,000
+The next transaction property is consistency and consistency ensures that we execute all the data changes
+
+71
+00:05:33,000 --> 00:05:40,000
+while maintaining a consistent state at the start and end of the transaction and data return to the
+
+72
+00:05:40,000 --> 00:05:48,000
+database must be valid according to all defined rules, including constraints, Cass case triggers and
+
+73
+00:05:48,000 --> 00:05:50,000
+any combinations thereof.
+
+74
+00:05:50,000 --> 00:05:57,000
+This prevents database corruption by an illegal transaction, but doesn't guarantee that the transaction
+
+75
+00:05:57,000 --> 00:05:58,000
+is correct.
+
+76
+00:05:58,000 --> 00:06:03,000
+Referential integrity guarantees the primary a key foreign key relationship.
+
+77
+00:06:04,000 --> 00:06:10,000
+A consistent state of data must conform to all the constraints that we define for data.
+
+78
+00:06:11,000 --> 00:06:18,000
+Let's not talk about his elation property transactions are often executed concurrently, multiple transactions
+
+79
+00:06:18,000 --> 00:06:21,000
+reading and writing to a table at the same time.
+
+80
+00:06:21,000 --> 00:06:28,000
+Isolation insurance is a concurrent execution of transactions, leaves the database in the same state
+
+81
+00:06:28,000 --> 00:06:30,000
+as it would have been obtained using.
+
+82
+00:06:30,000 --> 00:06:32,000
+Transactions were executed sequentially.
+
+83
+00:06:33,000 --> 00:06:40,000
+Isolation ensures that we keep the intermediate states of a transaction invisible to other transactions.
+
+84
+00:06:40,000 --> 00:06:45,000
+This gives concurrently run in transactions and the fact of being serialized.
+
+85
+00:06:46,000 --> 00:06:50,000
+The degree to which a transaction must be isolated from us.
+
+86
+00:06:50,000 --> 00:06:56,000
+A transaction is defined by isolation levels and the last but not the least, property is durability.
+
+87
+00:06:57,000 --> 00:07:03,000
+Your ability guarantees that once the transaction has been committed, it will remain committed even
+
+88
+00:07:03,000 --> 00:07:04,000
+in the case of a system failure.
+
+89
+00:07:05,000 --> 00:07:12,000
+For example, in cases of power outage or crash, and you remember, these are four main properties
+
+90
+00:07:12,000 --> 00:07:13,000
+of transactions.
+
+91
+00:07:13,000 --> 00:07:20,000
+Without these properties, it is hard to name as a transaction just a sequence of work items.
+
+92
+00:07:20,000 --> 00:07:22,000
+Hope that this is clear.
+
+93
+00:07:23,000 --> 00:07:29,000
+Like I said, these are also very important properties of transaction, like isolation levels and propagation.
+
+94
+00:07:29,000 --> 00:07:36,000
+Definitely, we can learn them now, but usually for my students, it is hard to understand this topic
+
+95
+00:07:36,000 --> 00:07:37,000
+was examples.
+
+96
+00:07:37,000 --> 00:07:44,000
+That's why I recommend to postpone learning such things as isolation levels and propagation property.
+
+97
+00:07:44,000 --> 00:07:52,000
+One will come to learn of Java Persistence API GPA because in that case, I will be able to show you
+
+98
+00:07:52,000 --> 00:07:57,000
+Dharma right after explaining Seri, we are transaction manager.
+
+99
+00:07:57,000 --> 00:08:04,000
+But in this lesson, we can focus on the transactions itself and its exit properties.
+
+100
+00:08:05,000 --> 00:08:06,000
+OK, let's move on.
+
+101
+00:08:07,000 --> 00:08:10,000
+Now we learn enough theory to proceed with examples.
+
+102
+00:08:10,000 --> 00:08:13,000
+Let me show you how we can manage transactions.
+
+103
+00:08:13,000 --> 00:08:19,000
+We are Giudice transaction example is located in the B c transaction example file.
+
+104
+00:08:20,000 --> 00:08:24,000
+All examples you will be able to find in attachments to the video.
+
+105
+00:08:25,000 --> 00:08:28,000
+Let's go line by line and see how it works.
+
+106
+00:08:28,000 --> 00:08:35,000
+In this example, we're going to make him money transfer from one user to another here and thought we
+
+107
+00:08:35,000 --> 00:08:37,000
+have to prepare SQL statements.
+
+108
+00:08:37,000 --> 00:08:45,000
+The first one is to update on for specific user I.D. and another one to select a user by its I.D..
+
+109
+00:08:46,000 --> 00:08:55,000
+After that, we configured my name is if we want to transfer user from I.D. and transfer to I.D. now
+
+110
+00:08:55,000 --> 00:08:57,000
+we are ready to make a money transfer.
+
+111
+00:08:57,000 --> 00:08:58,000
+We get connection object.
+
+112
+00:08:59,000 --> 00:09:02,000
+We prepare our statements for select and for update.
+
+113
+00:09:03,000 --> 00:09:09,000
+After that, I declare a reference to the safe point in the order it will be accessible in catch block.
+
+114
+00:09:10,000 --> 00:09:14,000
+Safe Point is an object that contains a state of the transaction.
+
+115
+00:09:14,000 --> 00:09:16,000
+This point was in.
+
+116
+00:09:16,000 --> 00:09:21,000
+The current transaction can be referenced from the rollback mass of connection object.
+
+117
+00:09:21,000 --> 00:09:27,000
+This is exactly the masses that will help us to restore the state of the transaction in a minute.
+
+118
+00:09:27,000 --> 00:09:34,000
+You are going to see how we can use that massive when transaction is rolled back through a sequence
+
+119
+00:09:34,000 --> 00:09:38,000
+of changes made after that save point are undone.
+
+120
+00:09:38,000 --> 00:09:41,000
+Save points can be easily named or unnamed.
+
+121
+00:09:42,000 --> 00:09:49,000
+Basically, during the creation of the save point, we can pass strings, name here and create name
+
+122
+00:09:49,000 --> 00:09:50,000
+save points.
+
+123
+00:09:51,000 --> 00:09:58,000
+After that, I try catch Block to handle all potential exceptions and low back transaction in case of
+
+124
+00:09:58,000 --> 00:09:59,000
+exception.
+
+125
+00:10:00,000 --> 00:10:01,000
+I need this in order.
+
+126
+00:10:01,000 --> 00:10:04,000
+My catching book would be within the tribe was resources block.
+
+127
+00:10:04,000 --> 00:10:11,000
+In order I could still have a reference to the connection object to roll back transaction in cash book.
+
+128
+00:10:12,000 --> 00:10:17,000
+And now I start my transaction in reading B.C. to take control of a transaction.
+
+129
+00:10:17,000 --> 00:10:19,000
+We have to set out to commit to false.
+
+130
+00:10:20,000 --> 00:10:27,000
+If a connection is an utter commitment, then all its sequel statements will be executed and committed
+
+131
+00:10:27,000 --> 00:10:29,000
+as individual transactions.
+
+132
+00:10:30,000 --> 00:10:36,000
+Otherwise, it's sequel statements are grouped into transactions that are terminated by a call to users.
+
+133
+00:10:36,000 --> 00:10:41,000
+A massive commit was the message rolled back manifold.
+
+134
+00:10:41,000 --> 00:10:44,000
+New connections are in order to commit more.
+
+135
+00:10:44,000 --> 00:10:47,000
+But with this set message, we can turn it off.
+
+136
+00:10:48,000 --> 00:10:56,000
+The first thing that I do is reading data about user from to make sure that the user has enough money
+
+137
+00:10:56,000 --> 00:10:57,000
+for money transfer.
+
+138
+00:10:57,000 --> 00:11:00,000
+In any case, user doesn't have enough money.
+
+139
+00:11:00,000 --> 00:11:02,000
+We just go.
+
+140
+00:11:02,000 --> 00:11:08,000
+It's massive and not proceeding was the next steps in case user have enough money for this transaction.
+
+141
+00:11:09,000 --> 00:11:13,000
+We deduct money amount and no data user in the database was reduced.
+
+142
+00:11:13,000 --> 00:11:14,000
+Money amount.
+
+143
+00:11:15,000 --> 00:11:19,000
+Theoretically, after some steps in transaction, you can make a save point.
+
+144
+00:11:20,000 --> 00:11:27,000
+For example, you have some logical steps combined together that makes sense to apply or to roll back
+
+145
+00:11:27,000 --> 00:11:31,000
+to that state and tries the following steps one more time.
+
+146
+00:11:31,000 --> 00:11:35,000
+In this case, you just need to revoke save points, mass.
+
+147
+00:11:36,000 --> 00:11:40,000
+You can pass through here to create name safe point.
+
+148
+00:11:40,000 --> 00:11:47,000
+In our particular case, we have only two steps, and logically, it makes no sense to save the state
+
+149
+00:11:47,000 --> 00:11:50,000
+only after reducing money amount for the first user.
+
+150
+00:11:51,000 --> 00:11:59,000
+After that, I select another user to add money a month to his mining value and update another user
+
+151
+00:11:59,000 --> 00:12:00,000
+in the database.
+
+152
+00:12:00,000 --> 00:12:04,000
+Once I updated users, I kokum, it's massive.
+
+153
+00:12:05,000 --> 00:12:12,000
+And now imagine SQL queries start being executed, and we already updated the first user.
+
+154
+00:12:12,000 --> 00:12:20,000
+But all of a sudden the lights went out and your database appeared to be without power at all.
+
+155
+00:12:20,000 --> 00:12:28,000
+And even more zeolite went out and the server using a Java app without power to you.
+
+156
+00:12:28,000 --> 00:12:30,000
+You don't have time to update the second user.
+
+157
+00:12:31,000 --> 00:12:32,000
+What to do now?
+
+158
+00:12:33,000 --> 00:12:40,000
+Java tracks as transaction, and apparently it detects some exceptional case happen in this case will
+
+159
+00:12:40,000 --> 00:12:42,000
+enter block.
+
+160
+00:12:42,000 --> 00:12:46,000
+And in case you look, I call back my sit on my connection object.
+
+161
+00:12:46,000 --> 00:12:53,000
+This massive insurance is a state that was before the transaction started will be restored in the database.
+
+162
+00:12:54,000 --> 00:12:56,000
+That's what we need in our case.
+
+163
+00:12:57,000 --> 00:13:00,000
+In some cases, you may roll back to the safe point.
+
+164
+00:13:01,000 --> 00:13:08,000
+This is not our case in this particular example, but I will keep this line command just for reference.
+
+165
+00:13:08,000 --> 00:13:11,000
+Basically, that's all we've got in this example.
+
+166
+00:13:12,000 --> 00:13:13,000
+This is how it is.
+
+167
+00:13:13,000 --> 00:13:16,000
+And then we can manage transactions with the help of GBC.
+
+168
+00:13:17,000 --> 00:13:24,000
+And the other thing is that I'd like to show you today is much updates this database and GDP C match
+
+169
+00:13:24,000 --> 00:13:30,000
+update is a bunch of updates grouped together and sent to a database in one much.
+
+170
+00:13:31,000 --> 00:13:38,000
+Rather than sending these updates one by one, sending a bunch of updates to the database in one go
+
+171
+00:13:38,000 --> 00:13:43,000
+is faster than sending them one by one, waiting for each one to finish.
+
+172
+00:13:44,000 --> 00:13:51,000
+There is less network traffic involved in sending one batch of updates only one round trip, and the
+
+173
+00:13:51,000 --> 00:13:55,000
+database might be able to execute some of the updates.
+
+174
+00:13:55,000 --> 00:14:02,000
+In parallel, the speed up compared to execute and set updates one by one can be quite big.
+
+175
+00:14:02,000 --> 00:14:07,000
+You can put on the Barge sequel, insert, update and delete statements.
+
+176
+00:14:08,000 --> 00:14:11,000
+It doesn't make sense to barge select statements.
+
+177
+00:14:12,000 --> 00:14:17,000
+Let me show you how you can execute batch updates is a database with legitimacy.
+
+178
+00:14:17,000 --> 00:14:21,000
+Well, examples from the lesson you can find in attachments to a video.
+
+179
+00:14:22,000 --> 00:14:23,000
+Just to remind.
+
+180
+00:14:24,000 --> 00:14:28,000
+Examples of his watch updates are located in the B c botch example.
+
+181
+00:14:29,000 --> 00:14:30,000
+Ever seen a single hit?
+
+182
+00:14:31,000 --> 00:14:32,000
+I create connection object.
+
+183
+00:14:33,000 --> 00:14:37,000
+Prepare statement we we're going to do three insertions in one batch.
+
+184
+00:14:38,000 --> 00:14:43,000
+In case you want, all insertions would be executed in one transaction.
+
+185
+00:14:43,000 --> 00:14:45,000
+You have to set out to commit the force.
+
+186
+00:14:46,000 --> 00:14:47,000
+But this is optional.
+
+187
+00:14:48,000 --> 00:14:54,000
+It is important to keep in mind is that each update added to the statement or prepared statement is
+
+188
+00:14:54,000 --> 00:14:56,000
+executed separately by the database.
+
+189
+00:14:57,000 --> 00:15:01,000
+That means that some of them may succeed before one of them fails.
+
+190
+00:15:02,000 --> 00:15:08,000
+All the statements that have succeeded are now applied to the database, but the rest of the updates
+
+191
+00:15:08,000 --> 00:15:09,000
+may not be.
+
+192
+00:15:09,000 --> 00:15:13,000
+This can result in an inconsistent data in the database.
+
+193
+00:15:14,000 --> 00:15:18,000
+That's why I recommend the use transactions during that much updates.
+
+194
+00:15:19,000 --> 00:15:26,000
+After that, you will feel out prepared statements was required values for all place holders, and once
+
+195
+00:15:26,000 --> 00:15:32,000
+you're done with each query, just invoke and punch massive and the same way I do with three groups
+
+196
+00:15:32,000 --> 00:15:41,000
+of parameters one I added All I wanted was a much I need to call execute large mass on my prepared statement
+
+197
+00:15:41,000 --> 00:15:45,000
+object and all match will be executed and sent as a database.
+
+198
+00:15:46,000 --> 00:15:47,000
+Is it clear?
+
+199
+00:15:48,000 --> 00:15:52,000
+Anyway, in case you will have any questions, do not hesitate to ask me.
+
+200
+00:15:52,000 --> 00:15:53,000
+Below this video.
+
+201
+00:15:54,000 --> 00:15:59,000
+And the last, but not the least, sing for the days that I'd like to discuss with you is how to explore
+
+202
+00:15:59,000 --> 00:16:01,000
+database method data programmatically.
+
+203
+00:16:02,000 --> 00:16:05,000
+Metadata means data about data.
+
+204
+00:16:05,000 --> 00:16:13,000
+For example, you might need to explore what tables you have in this database or you might want to investigate
+
+205
+00:16:13,000 --> 00:16:16,000
+what columns this or another table has.
+
+206
+00:16:16,000 --> 00:16:19,000
+This will help you to build dynamic queries.
+
+207
+00:16:20,000 --> 00:16:25,000
+My same dynamic queries, I mean, you will be able to investigate the structure of the database on
+
+208
+00:16:25,000 --> 00:16:31,000
+the fly during the program execution, depending on the business logic of your app.
+
+209
+00:16:31,000 --> 00:16:38,000
+This might come in handy sometimes, and definitely you have to know about such possibility in Java.
+
+210
+00:16:39,000 --> 00:16:45,000
+The main interface that provides a variety of methods to obtain information about the database is called
+
+211
+00:16:45,000 --> 00:16:46,000
+database metadata.
+
+212
+00:16:47,000 --> 00:16:49,000
+Let me open its source code.
+
+213
+00:16:50,000 --> 00:16:55,000
+You can explore multiple masses and also you can see that there are really a lot of them here.
+
+214
+00:16:55,000 --> 00:17:02,000
+We are not going to know and review each of these masses, but definitely the amount of mass is listed
+
+215
+00:17:02,000 --> 00:17:08,000
+here is more than enough for building tool or even an application for interactive database interaction
+
+216
+00:17:08,000 --> 00:17:13,000
+because you have opportunity to explore a lot of information about database.
+
+217
+00:17:13,000 --> 00:17:20,000
+Let's open our demo files at scope database metadata example where I prepared for you.
+
+218
+00:17:20,000 --> 00:17:27,000
+All examples related to interaction was a database metadata, and the first thing that I do here is
+
+219
+00:17:27,000 --> 00:17:33,000
+get into the referenced database metadata object using the reference to the connection object.
+
+220
+00:17:34,000 --> 00:17:37,000
+Now, let's extract information about all tables.
+
+221
+00:17:37,000 --> 00:17:41,000
+I call get tables massive of mine method data object.
+
+222
+00:17:42,000 --> 00:17:45,000
+Yeah, different parameters here is that I don't populate.
+
+223
+00:17:46,000 --> 00:17:47,000
+What are they?
+
+224
+00:17:47,000 --> 00:17:51,000
+The first two parameters are catalog and scheme.
+
+225
+00:17:51,000 --> 00:17:55,000
+According the search parameter takes a table name part.
+
+226
+00:17:56,000 --> 00:18:02,000
+For example, if I write, ProArt was person sign similar to the same things that we used in.
+
+227
+00:18:02,000 --> 00:18:09,000
+Like Operator, this will include all the tables whose name starts with prop.
+
+228
+00:18:09,000 --> 00:18:18,000
+The last parameter takes a string array containing the types of tables used use table for user defined
+
+229
+00:18:18,000 --> 00:18:26,000
+tables, so all table types use massive get table types, often locational get tables.
+
+230
+00:18:26,000 --> 00:18:27,000
+Massive will receive results.
+
+231
+00:18:27,000 --> 00:18:35,000
+That was table info, and it will iterate over a result set to get table names and bring it to consult.
+
+232
+00:18:36,000 --> 00:18:38,000
+You can retrieve it by table name.
+
+233
+00:18:38,000 --> 00:18:39,000
+Column name.
+
+234
+00:18:41,000 --> 00:18:44,000
+But let's imagine that you don't know how columns are called.
+
+235
+00:18:45,000 --> 00:18:46,000
+Could it be so?
+
+236
+00:18:47,000 --> 00:18:48,000
+Yes, absolutely.
+
+237
+00:18:49,000 --> 00:18:50,000
+And what to do?
+
+238
+00:18:51,000 --> 00:18:53,000
+You can get the metadata of your results set.
+
+239
+00:18:54,000 --> 00:19:00,000
+Let me show you how you can easily iterate over all columns and then all column names.
+
+240
+00:19:01,000 --> 00:19:06,000
+But on the example of table types, because we also want to see a table.
+
+241
+00:19:07,000 --> 00:19:08,000
+But how did you know?
+
+242
+00:19:08,000 --> 00:19:12,000
+Let's get the results said by Colin, get table types.
+
+243
+00:19:12,000 --> 00:19:17,000
+And after that call, get that data massive on the results that object.
+
+244
+00:19:17,000 --> 00:19:20,000
+Now you will get results set and that the data.
+
+245
+00:19:21,000 --> 00:19:26,000
+Having this result sets method data, I can announce how many columns we have.
+
+246
+00:19:26,000 --> 00:19:34,000
+And after that, I can iterate over each row to get the value from each column by iterating over each
+
+247
+00:19:34,000 --> 00:19:35,000
+column in the results set.
+
+248
+00:19:36,000 --> 00:19:43,000
+And here you can see consoles that can be printed all values from the result set without known column
+
+249
+00:19:43,000 --> 00:19:45,000
+names and the amount of malice at all.
+
+250
+00:19:46,000 --> 00:19:50,000
+Can you see how cool it is to dynamically investigates a database?
+
+251
+00:19:51,000 --> 00:19:58,000
+You can explore even more by navigating through the source code of results, set metadata and database
+
+252
+00:19:58,000 --> 00:19:58,000
+metadata.
+
+253
+00:19:59,000 --> 00:20:01,000
+Take my code examples.
+
+254
+00:20:01,000 --> 00:20:06,000
+Play with this code, and I hope you will be able to learn more about method data in practice.
+
+255
+00:20:07,000 --> 00:20:08,000
+That's it for today.
+
+256
+00:20:09,000 --> 00:20:15,000
+Let's recap what we have learned today in this lesson, we learned what transactions are.
+
+257
+00:20:16,000 --> 00:20:19,000
+Also now, you know, the properties of transactions.
+
+258
+00:20:19,000 --> 00:20:23,000
+We learned what properties are after that.
+
+259
+00:20:23,000 --> 00:20:30,000
+A real example scenario runs how to manage transactions with the B c, you saw examples of commit safe
+
+260
+00:20:30,000 --> 00:20:32,000
+buying and rolled back commands.
+
+261
+00:20:33,000 --> 00:20:36,000
+Review how to execute match updates to the database.
+
+262
+00:20:37,000 --> 00:20:43,000
+And examples amassing in-and how to work with database metadata as a result sets metadata.
+
+263
+00:20:44,000 --> 00:20:45,000
+That's it for today.
+
+264
+00:20:45,000 --> 00:20:47,000
+Thanks a lot for your attention.
+
+265
+00:20:47,000 --> 00:20:50,000
+Have a great day and see you in the next lesson.
+

52 - JDBC/external-links.txt

@@ -0,0 +1,9 @@
+
+001 Source-code-example-from-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc
+
+002 Source-code-example-from-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc
+
+003 Source-code-example-from-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/jdbc

53 - DAO/001 DAO (Data Access Object) Design Pattern_en.srt

@@ -0,0 +1,920 @@
+1
+00:00:06,000 --> 00:00:12,000
+Hello, distance in this lesson we're going to learn now partner and review examples, how to apply.
+
+2
+00:00:13,000 --> 00:00:16,000
+We're going to start the lesson from the problem statement.
+
+3
+00:00:17,000 --> 00:00:23,000
+We'll discuss what problem potentially we might face with and the only after that we'll proceed with
+
+4
+00:00:23,000 --> 00:00:30,000
+Dow Pot and you'll understand our part is and what its main elements.
+
+5
+00:00:31,000 --> 00:00:38,000
+We're going to review a sequence diagram where I will explain you and flow of Dow Pot.
+
+6
+00:00:38,000 --> 00:00:42,000
+Also, we're going to learn what data transfer object this.
+
+7
+00:00:42,000 --> 00:00:49,000
+And on the real example I'm going to show you is a card that demonstrates how Pardon may be implemented
+
+8
+00:00:49,000 --> 00:00:55,000
+in practice all code examples you will be able to find in attachments to the lesson.
+
+9
+00:00:55,000 --> 00:00:56,000
+Let's stop.
+
+10
+00:00:57,000 --> 00:01:02,000
+Let's start from understanding the problems and how parents are supposed to help us to solve.
+
+11
+00:01:03,000 --> 00:01:05,000
+Now stands for data access object.
+
+12
+00:01:06,000 --> 00:01:12,000
+Imagine that you have application during my Java course, together with students, we develop our own
+
+13
+00:01:12,000 --> 00:01:16,000
+online shop and to implement online shop.
+
+14
+00:01:16,000 --> 00:01:23,000
+We need persistent storage in that storage where I want to store application related data like information
+
+15
+00:01:23,000 --> 00:01:27,000
+about our users products, orders and purchases, for example.
+
+16
+00:01:28,000 --> 00:01:35,000
+Well, you learned how to interact with the data is a persistent storage in our database section of
+
+17
+00:01:35,000 --> 00:01:36,000
+the course.
+
+18
+00:01:36,000 --> 00:01:42,000
+Now, you know how to interact with our relational database with the help of GBC API.
+
+19
+00:01:43,000 --> 00:01:50,000
+And if you didn't watch lessons about JTBC API, I recommend it to do so because this is important to
+
+20
+00:01:50,000 --> 00:01:53,000
+understand the code examples from this lesson.
+
+21
+00:01:53,000 --> 00:02:00,000
+Now, in the relational database management systems, you already know that sometimes not very often,
+
+22
+00:02:00,000 --> 00:02:04,000
+but sometimes there is might be different syntax, even in SQL statements.
+
+23
+00:02:05,000 --> 00:02:11,000
+And I'm not even talking about different persistent storages because for relational databases, you
+
+24
+00:02:11,000 --> 00:02:14,000
+are going to use a B C API in one way.
+
+25
+00:02:14,000 --> 00:02:17,000
+But the way how you interact was not relational.
+
+26
+00:02:17,000 --> 00:02:24,000
+Database is different, and you may have different data sources in your app, and you would need actually
+
+27
+00:02:24,000 --> 00:02:27,000
+change in your code impacting your other codes.
+
+28
+00:02:27,000 --> 00:02:34,000
+It relies on this one to make sure that you can fetch and update data in persistent storage.
+
+29
+00:02:35,000 --> 00:02:41,000
+And if you remember well, from my object oriented programming course, when we discussed principles
+
+30
+00:02:41,000 --> 00:02:49,000
+of code design, we learned one important rule that dependency should go in the direction of stability
+
+31
+00:02:50,000 --> 00:02:50,000
+and persistence.
+
+32
+00:02:50,000 --> 00:02:58,000
+They're usually considered as one of the stable layers and a lot of code in your app dependant on your
+
+33
+00:02:58,000 --> 00:02:59,000
+persistence there.
+
+34
+00:03:00,000 --> 00:03:06,000
+And if you decide to modify it or change anyhow, you're going to face with a lot of difficulties.
+
+35
+00:03:07,000 --> 00:03:14,000
+Now, pardon supposed to solve this problem by declaring an abstraction layer that interacts with business
+
+36
+00:03:14,000 --> 00:03:20,000
+objects was down upon you encapsulate the point of access to data in the app.
+
+37
+00:03:20,000 --> 00:03:22,000
+So what do our partners about?
+
+38
+00:03:23,000 --> 00:03:31,000
+Wearing a shirt and in simplified words, now declare a set of interfaces for components in your app
+
+39
+00:03:31,000 --> 00:03:34,000
+to interact with the persistent storage.
+
+40
+00:03:34,000 --> 00:03:41,000
+This API is supposed to stay stable and oriented on business side and terminology of your app.
+
+41
+00:03:42,000 --> 00:03:44,000
+The API should be as simple as possible.
+
+42
+00:03:45,000 --> 00:03:52,000
+For example, nobody cares how many joint queries you should do to fetch or a history of specific user
+
+43
+00:03:52,000 --> 00:03:55,000
+you need to fetch his or that history.
+
+44
+00:03:55,000 --> 00:04:03,000
+And that's it, because in case you migrate to another database, there might even not be anything worse.
+
+45
+00:04:03,000 --> 00:04:06,000
+And there is no reason for joints at all.
+
+46
+00:04:06,000 --> 00:04:11,000
+But the business activity business action, which still remains the same.
+
+47
+00:04:12,000 --> 00:04:16,000
+Your app still need to fetch or a history of specific user.
+
+48
+00:04:17,000 --> 00:04:18,000
+Does it make sense?
+
+49
+00:04:18,000 --> 00:04:27,000
+Implementation of down interfaces count on specifics of systems that we interact with that can be different.
+
+50
+00:04:27,000 --> 00:04:32,000
+Persistent storages and all specifics are described in our implementations.
+
+51
+00:04:33,000 --> 00:04:39,000
+Now, implementations encapsulates and hides all the details from decline.
+
+52
+00:04:40,000 --> 00:04:46,000
+And when you change the source of the data in your app, the actual interfaces remains the same for
+
+53
+00:04:46,000 --> 00:04:47,000
+business components.
+
+54
+00:04:48,000 --> 00:04:51,000
+That's the beauty and reason of using Dolly Parton.
+
+55
+00:04:52,000 --> 00:04:53,000
+Is it more clear now?
+
+56
+00:04:54,000 --> 00:04:57,000
+Now, let's review this part and closer.
+
+57
+00:04:57,000 --> 00:05:01,000
+Let's understand what elements of our partner we are dealing with.
+
+58
+00:05:01,000 --> 00:05:04,000
+You can see class diagram on the screen.
+
+59
+00:05:05,000 --> 00:05:13,000
+We have business object that uses data access object that in turn encapsulates access to our data source.
+
+60
+00:05:13,000 --> 00:05:16,000
+This can be our relational database.
+
+61
+00:05:16,000 --> 00:05:24,000
+For example, data access object creates and uses data transfer object business object receives and
+
+62
+00:05:24,000 --> 00:05:27,000
+adjust our data transfer object.
+
+63
+00:05:27,000 --> 00:05:33,000
+Press pause for a few seconds just to watch this diagram one more time.
+
+64
+00:05:33,000 --> 00:05:39,000
+And don't worry, we're going to look at not a diagram that should address some of your questions.
+
+65
+00:05:40,000 --> 00:05:47,000
+Let's look at the sequence diagram to understand how all these elements are connected to each other.
+
+66
+00:05:47,000 --> 00:05:52,000
+You're in the entrance slope and to help you understand this flow better.
+
+67
+00:05:52,000 --> 00:05:56,000
+Let's imagine that this flow describes user log in process.
+
+68
+00:05:57,000 --> 00:06:00,000
+The first step here goes Who does business object?
+
+69
+00:06:01,000 --> 00:06:01,000
+What it is?
+
+70
+00:06:02,000 --> 00:06:05,000
+Business object is a client of our data.
+
+71
+00:06:06,000 --> 00:06:07,000
+It can be some service.
+
+72
+00:06:07,000 --> 00:06:14,000
+For example, imagine that we have log in service that makes sure that it's credentials provided by
+
+73
+00:06:14,000 --> 00:06:15,000
+user valid.
+
+74
+00:06:16,000 --> 00:06:22,000
+This kind of object requires access to the data source in order to perform its work.
+
+75
+00:06:23,000 --> 00:06:27,000
+First of all, this object aggregates the object inside itself.
+
+76
+00:06:28,000 --> 00:06:35,000
+We can see that the business object creates a reference to the object, but dependent on the technical
+
+77
+00:06:35,000 --> 00:06:37,000
+approach of our application.
+
+78
+00:06:37,000 --> 00:06:46,000
+The object also may exist as a single time and be injected into a business object during its instantiation.
+
+79
+00:06:46,000 --> 00:06:52,000
+We're going to learn later and now, of course, dependency injection and you'll understand what I mean.
+
+80
+00:06:53,000 --> 00:06:58,000
+Anyway, after the first step business object calls or references and object.
+
+81
+00:06:59,000 --> 00:07:05,000
+This object is an abstraction level that provides single and stable application programming interface
+
+82
+00:07:05,000 --> 00:07:10,000
+to our business object to interact with provide an access to the data source.
+
+83
+00:07:11,000 --> 00:07:18,000
+The second step at some point of time business object requests the object to get some data.
+
+84
+00:07:19,000 --> 00:07:23,000
+Now, in turn, encapsulates all low level details.
+
+85
+00:07:23,000 --> 00:07:31,000
+The implementation of the object knows how to interact with a specific data source and in case data
+
+86
+00:07:31,000 --> 00:07:32,000
+source will be changed.
+
+87
+00:07:32,000 --> 00:07:38,000
+You have to change on the implementation of the data object, but not the whole interface.
+
+88
+00:07:39,000 --> 00:07:43,000
+Basically, nothing will be changed for business object.
+
+89
+00:07:44,000 --> 00:07:46,000
+Let's go further now.
+
+90
+00:07:46,000 --> 00:07:49,000
+Object requests the data from data source.
+
+91
+00:07:50,000 --> 00:07:56,000
+Imagine that we extract the user object from the database to check that log in and password provided
+
+92
+00:07:56,000 --> 00:07:59,000
+by business object matches a once stored in the database.
+
+93
+00:08:00,000 --> 00:08:01,000
+No object?
+
+94
+00:08:01,000 --> 00:08:03,000
+Create data transfer object.
+
+95
+00:08:04,000 --> 00:08:08,000
+I will use term detail that stands for data transfer.
+
+96
+00:08:08,000 --> 00:08:16,000
+Object is a clear data transfer object contains action is the data that is needed to our business object.
+
+97
+00:08:17,000 --> 00:08:17,000
+It can be.
+
+98
+00:08:17,000 --> 00:08:25,000
+User data was all information about our user path, and that data is just a data structure.
+
+99
+00:08:26,000 --> 00:08:29,000
+It doesn't have any behavior, actually.
+
+100
+00:08:29,000 --> 00:08:34,000
+It may contain getters and setters, but this is not business related behavior.
+
+101
+00:08:34,000 --> 00:08:39,000
+This reference is an object oriented section of the course to learn more.
+
+102
+00:08:39,000 --> 00:08:43,000
+What is the difference between data structure and object business?
+
+103
+00:08:43,000 --> 00:08:52,000
+Object and charm may set new property value into detail and parse updated detail back to that object
+
+104
+00:08:53,000 --> 00:09:01,000
+and ask that the state of the data and the persistent storage, for example, imagines that the user
+
+105
+00:09:01,000 --> 00:09:05,000
+decided to change his mobile phone number and the profile.
+
+106
+00:09:06,000 --> 00:09:08,000
+We have added the phone number in our detail.
+
+107
+00:09:09,000 --> 00:09:16,000
+This data may be updated by the specific service inside our app, and after that, our business object
+
+108
+00:09:16,000 --> 00:09:18,000
+sends updated details.
+
+109
+00:09:18,000 --> 00:09:23,000
+This the object, and we update the state of this data and our data source.
+
+110
+00:09:24,000 --> 00:09:33,000
+So what would you see now is more or less going now about now pardon and probably zone only things that
+
+111
+00:09:33,000 --> 00:09:37,000
+we are missing now for better understanding of Dolly Parton is a life example.
+
+112
+00:09:38,000 --> 00:09:44,000
+Let's jump a good example and review real life scenario based on our online shop application.
+
+113
+00:09:45,000 --> 00:09:48,000
+Let's start from the definition of the Doll API.
+
+114
+00:09:49,000 --> 00:09:56,000
+In this example, we are going to create together User Doll API is defined in the interface.
+
+115
+00:09:56,000 --> 00:09:59,000
+Let's review what assets are defined here.
+
+116
+00:10:00,000 --> 00:10:06,000
+First of all, I ask myself what business related cases my dolls should address.
+
+117
+00:10:07,000 --> 00:10:08,000
+This is extracting the user by ID.
+
+118
+00:10:09,000 --> 00:10:17,000
+Also, I need to be able to extract user by email because we use email duran's and log in and we need
+
+119
+00:10:17,000 --> 00:10:19,000
+to be able to extract user.
+
+120
+00:10:20,000 --> 00:10:24,000
+Also, we need the possibility to save user and our persistent storage.
+
+121
+00:10:25,000 --> 00:10:28,000
+That's why I have this list of methods.
+
+122
+00:10:28,000 --> 00:10:36,000
+Yet the user by any user, by email and safe user in times that we work with here, I decided to call
+
+123
+00:10:36,000 --> 00:10:40,000
+it user detail because we have just reviewed what data?
+
+124
+00:10:40,000 --> 00:10:41,000
+Transfer object, yes.
+
+125
+00:10:42,000 --> 00:10:47,000
+And in this particular example, I will interact with pure data structure.
+
+126
+00:10:47,000 --> 00:10:51,000
+I want to say that one, you will become experienced developer.
+
+127
+00:10:51,000 --> 00:10:57,000
+You're going to have your own point of view how to name this site because there is a slight difference
+
+128
+00:10:57,000 --> 00:10:57,000
+in naming.
+
+129
+00:10:58,000 --> 00:11:05,000
+For example, you can names the dog not like user data, but just use it, for example, or you can
+
+130
+00:11:05,000 --> 00:11:09,000
+name it, user model fallen and receive part.
+
+131
+00:11:09,000 --> 00:11:13,000
+We're going to talk with MVC partners in the separate lesson.
+
+132
+00:11:14,000 --> 00:11:21,000
+But even different frameworks like Congress from SAP or other eCommerce frameworks that already contain
+
+133
+00:11:21,000 --> 00:11:27,000
+predefined structure and layouts of classes uses the same terminology in different way.
+
+134
+00:11:28,000 --> 00:11:30,000
+So don't judge me here.
+
+135
+00:11:31,000 --> 00:11:34,000
+Just know that there are different points of view on the same since.
+
+136
+00:11:35,000 --> 00:11:39,000
+But the main idea is to understand the sense of what we are doing here.
+
+137
+00:11:40,000 --> 00:11:46,000
+And in this particular case, we need to have some data structures that will transfer data from one
+
+138
+00:11:46,000 --> 00:11:48,000
+layer of our app to another.
+
+139
+00:11:48,000 --> 00:11:51,000
+Let's create our data types now.
+
+140
+00:11:51,000 --> 00:11:56,000
+This type should describe properties that exist in the database.
+
+141
+00:11:56,000 --> 00:12:05,000
+In our specific case, our user has the following properties ID, first name, last name, email role,
+
+142
+00:12:06,000 --> 00:12:09,000
+money, credit card and pay attention.
+
+143
+00:12:09,000 --> 00:12:13,000
+That is, a database user role is just a foreign key.
+
+144
+00:12:13,000 --> 00:12:17,000
+One will learn Java Persistence API GP.
+
+145
+00:12:17,000 --> 00:12:23,000
+You are going to learn that it will be enough just to set correct relationship between different entities
+
+146
+00:12:24,000 --> 00:12:28,000
+and will handle fetch of all related data by foreign key.
+
+147
+00:12:29,000 --> 00:12:37,000
+So we should use real time and user data, but not just in value to store foreign key because inside
+
+148
+00:12:37,000 --> 00:12:46,000
+our app, we are interested in the actual role of the user, but not well and the understand this point.
+
+149
+00:12:47,000 --> 00:12:53,000
+And also imagine that you don't want to store money in double value, but instead you want to operate
+
+150
+00:12:53,000 --> 00:12:55,000
+was big that small money rally in the app.
+
+151
+00:12:56,000 --> 00:13:03,000
+This is also might be considered on this abstraction level, and your down object will be in charge
+
+152
+00:13:03,000 --> 00:13:08,000
+for populating your object with the data that you are interested in and in specified form.
+
+153
+00:13:09,000 --> 00:13:13,000
+Because such kind of details will be described in the Dart implementation.
+
+154
+00:13:14,000 --> 00:13:23,000
+That's why I need to declare also all the oil that will store rolling and will name potentials at the
+
+155
+00:13:23,000 --> 00:13:25,000
+most data or objects that we created.
+
+156
+00:13:26,000 --> 00:13:31,000
+Also have getters and setters and also for debugging purposes.
+
+157
+00:13:31,000 --> 00:13:38,000
+I override the strength massive in order we can seize a state of the object and console you as a demo.
+
+158
+00:13:39,000 --> 00:13:42,000
+So what are we supposed to do next?
+
+159
+00:13:42,000 --> 00:13:47,000
+The next things that we need to do is to implement our dart interface.
+
+160
+00:13:48,000 --> 00:13:49,000
+So that's good.
+
+161
+00:13:50,000 --> 00:13:54,000
+I create my sequel to the PC user now from its name.
+
+162
+00:13:54,000 --> 00:13:57,000
+You already can understand that is down.
+
+163
+00:13:57,000 --> 00:14:03,000
+Pigmentation will consider all specifics of interacting with my school relational database through the
+
+164
+00:14:03,000 --> 00:14:05,000
+GBC API.
+
+165
+00:14:05,000 --> 00:14:13,000
+This class implements my user now, and if you watched my lessons about GDC, you already know how to
+
+166
+00:14:13,000 --> 00:14:17,000
+establish connections as a database and extract results.
+
+167
+00:14:17,000 --> 00:14:18,000
+That was user info.
+
+168
+00:14:19,000 --> 00:14:21,000
+But Sampson will be different.
+
+169
+00:14:21,000 --> 00:14:28,000
+Let's review, for example, gets user body mass of those key cards that you already know where I establish
+
+170
+00:14:28,000 --> 00:14:32,000
+connection, executes sequel query and gets the results set.
+
+171
+00:14:33,000 --> 00:14:40,000
+So once we get results set, we can create our detailed object and populate all fields, setters, masses.
+
+172
+00:14:41,000 --> 00:14:47,000
+Later in this course, we are going to learn how to avoid common, said Mascot for each property using
+
+173
+00:14:47,000 --> 00:14:49,000
+Java Persistence API.
+
+174
+00:14:50,000 --> 00:14:55,000
+But if you use it, we see that is the way to go and from one side.
+
+175
+00:14:55,000 --> 00:14:57,000
+This is very flexible.
+
+176
+00:14:57,000 --> 00:15:04,000
+You have control over each property population in your detail object, but from another site it can
+
+177
+00:15:04,000 --> 00:15:08,000
+be difficult to populate all fields in big objects.
+
+178
+00:15:09,000 --> 00:15:17,000
+The Populates Road property I use rolled down an extractor, all via its I.D. that is also a closet
+
+179
+00:15:17,000 --> 00:15:18,000
+we have to create.
+
+180
+00:15:19,000 --> 00:15:21,000
+The algorithm is the same.
+
+181
+00:15:22,000 --> 00:15:29,000
+We establish connection, execute query to DB populate values from results set in the Java object,
+
+182
+00:15:30,000 --> 00:15:40,000
+and we recount a roll detail from the mess that is set to the user object and when all fields of user.
+
+183
+00:15:40,000 --> 00:15:43,000
+Object of a populated, a return user from mass.
+
+184
+00:15:44,000 --> 00:15:50,000
+Let me open down them a class that I created to demonstrate how these examples are.
+
+185
+00:15:51,000 --> 00:15:52,000
+Let me run this.
+
+186
+00:15:54,000 --> 00:15:54,000
+I agree.
+
+187
+00:15:54,000 --> 00:16:02,000
+My the PC users, though object and one to extract user was its help and income.
+
+188
+00:16:02,000 --> 00:16:08,000
+So you can see that when I extract user Biney, I receive relevant information from the database.
+
+189
+00:16:09,000 --> 00:16:17,000
+But inside my application, I can use not results that object that contains values, but true object.
+
+190
+00:16:18,000 --> 00:16:22,000
+I can pass this object to different mascots as massive argument.
+
+191
+00:16:23,000 --> 00:16:27,000
+I can change its state and interact with it in object oriented way.
+
+192
+00:16:28,000 --> 00:16:29,000
+Does it make sense?
+
+193
+00:16:29,000 --> 00:16:33,000
+Can you understand now how all this code is connected?
+
+194
+00:16:34,000 --> 00:16:41,000
+And from now on, I can inject this now object everywhere I need, no matter whether this is checkouts,
+
+195
+00:16:41,000 --> 00:16:45,000
+service or logging service that contains any business logic.
+
+196
+00:16:45,000 --> 00:16:49,000
+I have a single point of data access that is user Dow.
+
+197
+00:16:50,000 --> 00:16:58,000
+And in case of change in data source zone, the scenes that will be impacted is the implementation.
+
+198
+00:16:59,000 --> 00:17:02,000
+All the Dow interfaces will remain the same.
+
+199
+00:17:03,000 --> 00:17:09,000
+Now, let's quickly review implementation of ASM Mass to make sure that these examples are clear to
+
+200
+00:17:09,000 --> 00:17:09,000
+you.
+
+201
+00:17:10,000 --> 00:17:12,000
+Yeah, it's user by email.
+
+202
+00:17:12,000 --> 00:17:14,000
+Mass at is very, very similar to the previous one.
+
+203
+00:17:15,000 --> 00:17:16,000
+There is only one difference.
+
+204
+00:17:17,000 --> 00:17:19,000
+We use email instead of ID.
+
+205
+00:17:20,000 --> 00:17:20,000
+That's it.
+
+206
+00:17:21,000 --> 00:17:23,000
+The algorithm is the same.
+
+207
+00:17:23,000 --> 00:17:28,000
+And in our demo, you can see how I extracted the same user by email.
+
+208
+00:17:29,000 --> 00:17:31,000
+You said mass, it is slightly different.
+
+209
+00:17:32,000 --> 00:17:34,000
+I have to say if user in the database.
+
+210
+00:17:34,000 --> 00:17:42,000
+How I do that, I pass user data object does it, though, and now will translate the commands from
+
+211
+00:17:42,000 --> 00:17:48,000
+object oriented language in the specific language of instructions or specific persistent storage.
+
+212
+00:17:49,000 --> 00:17:57,000
+In this case, we have different sequel statements to insert new row in the database, and we use user
+
+213
+00:17:57,000 --> 00:18:02,000
+argument to get the data was get their massive to populate in sequel statement.
+
+214
+00:18:03,000 --> 00:18:10,000
+After execution of this mass of information about this user will be stored in the database and the demo
+
+215
+00:18:10,000 --> 00:18:14,000
+clause I call safe user message and drive.
+
+216
+00:18:14,000 --> 00:18:22,000
+After that, I extract the user by the email of our new user, and in console you can see that I successfully
+
+217
+00:18:22,000 --> 00:18:25,000
+extracted the user that I have just added to the database.
+
+218
+00:18:26,000 --> 00:18:27,000
+Is it clear?
+
+219
+00:18:28,000 --> 00:18:35,000
+And that's how easy I can move data around database and my Java application using simple dot interface
+
+220
+00:18:36,000 --> 00:18:40,000
+and the objects as single data access to my persistent storage.
+
+221
+00:18:41,000 --> 00:18:47,000
+In case you still have any questions, you are more than welcome to ask all of your questions in the
+
+222
+00:18:47,000 --> 00:18:48,000
+comments to this video.
+
+223
+00:18:49,000 --> 00:18:50,000
+That's all for this lesson.
+
+224
+00:18:51,000 --> 00:18:59,000
+Let's recap what we have learned today in this lesson, we've learned what our power is, you know,
+
+225
+00:18:59,000 --> 00:19:03,000
+what is the main elements and active parts of our part?
+
+226
+00:19:04,000 --> 00:19:10,000
+Also revealed sequence diagram where a visual artist has an intense flow was now part, and we'll look
+
+227
+00:19:11,000 --> 00:19:12,000
+after this lesson.
+
+228
+00:19:12,000 --> 00:19:19,000
+You already know what data transfer object is and do you of is your real life example was Dolly Parton
+
+229
+00:19:20,000 --> 00:19:22,000
+sings a lot of the students for your attention.
+
+230
+00:19:23,000 --> 00:19:25,000
+Have a great day and see you in the next lesson.
+

53 - DAO/001 Source-code-example-from-the-lesson.url

@@ -0,0 +1,2 @@
+[InternetShortcut]
+URL=https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/dao

53 - DAO/external-links.txt

@@ -0,0 +1,3 @@
+
+001 Source-code-example-from-the-lesson
+https://github.com/AndriiPiatakha/learnit_java_core/tree/master/src/com/itbulls/learnit/javacore/dao

54 - ===== JDBC, SQL & Databases Interview Preparation =====/001 Part 1 JDBC & Databases - Questions and Answers.html

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+<html lang="en">
+    <head>
+        <meta charset="UTF-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>Part 1 JDBC & Databases - Questions and Answers</title>
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+    <body>
+        <div class="container">
+            <div class="content">
+                <div class="heading">Part 1 JDBC & Databases - Questions and Answers</div>
+                <div class="article-asset-container"><ul><li><p><strong>WHAT IS JDBC?</strong></p></li></ul><p><br></p><p>The JDBC (Java DataBase Connectivity) API is a standard Java application interface for organizing interaction between an application and a DBMS. Interaction is carried out using JDBC drivers, which provide implementations of common interfaces for specific DBMS and specific protocols. JDBC defines four types of drivers.</p><p><br></p><p><br></p><ul><li><p><strong>STEPS OF WORKING WITH A DATABASE USING JDBC?</strong></p></li></ul><p><br></p><p>Steps for working with a database using JDBC:</p><ul><li><p>Connecting a library with a database driver class.</p></li><li><p>Establishing a connection to the database.</p></li><li><p>Create an object to send requests.</p></li><li><p>Execution of a request.</p></li><li><p>Processing the results of query execution.</p></li><li><p>Closing the connection, statement</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>HOW TO CREATE A CONNECTION?</strong></p></li></ul><p><br></p><p>To establish a connection to the database, the static getConnection() method of the java.sql.DriverManager class is called. As parameters to the method we have to pass the database URL, database user login and access password. Loading a database driver class when there is no reference to an instance of this class in JDBC 4.1 occurs automatically when a connection is established by the DriverManager instance. The method returns a Connection object. The database URL, consisting of the type and address of the physical location of the database, can be created as a separate string or retrieved from a resource file.</p><p><br></p><p><br></p><ul><li><p><strong>HOW IS STATEMENT DIFFERENT FROM PREPAREDSTATEMENT?</strong></p></li></ul><p><br></p><p>The Statement object is used to execute SQL queries against the database. There are three types of Statement objects. All three serve as containers for executing SQL statements through this connection: Statement, PreparedStatement, which inherits from Statement, and CallableStatement, which inherits from PreparedStatement. They specialize in different types of queries: Statement is used to execute simple SQL queries without parameters; PreparedStatement is used to execute precompiled SQL queries with or without input (IN) parameters; CallableStatement is used to call stored procedures.</p><p><br></p><p>The Statement interface provides basic methods for executing queries and retrieving results. The PreparedStatement interface adds methods for managing input (IN) parameters; CallableStatement adds methods for manipulating OUT parameters.</p><p><br></p><p>The PreparedStatement interface inherits from Statement and differs from the latter in the following ways:</p><ul><li><p>Instances of PreparedStatement "remember" compiled SQL statements. That is why they are called "prepared".</p></li><li><p>SQL statements in a PreparedStatement can have one or more input (IN) parameters. An input parameter is a parameter whose value is not specified when the SQL statement is created. Instead, in the expression, the sign ("?") is put in place of each input parameter. The value of each question mark is set by the setXXX methods before the request is executed.</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>HOW TO CALL A STORED PROCEDURE?</strong></p></li></ul><p><br></p><p>Stored procedures are a named set of Transact-SQL statements stored on a server. Such a procedure can be easily called from a Java class using special syntax. When calling such a procedure, you must specify its name and define a list of parameters. The name and parameter list are sent over a JDBC connection to the DBMS, which executes the called procedure and returns the result (if any) back using the same connection.</p><p><br></p><p><br></p><ul><li><p><strong>HOW TO CLOSE THE CONNECTION CORRECTLY?</strong></p></li></ul><p><br></p><p>Once the database is no longer needed, the connection is closed. Java 7 introduces try with resources for resource objects that require closures. So, usually, we specify resources in try-with-resources block.</p><p><br></p><p>In case you can’t use the mentioned block, resources should be closed in final block.</p><p><br></p><ul><li><p><strong>WHAT ARE THE LEVELS OF TRANSACTION ISOLATION?</strong></p></li></ul><p><br></p><p>Transaction isolation levels are defined as interface constants</p><p>Connection (ascending restriction level):</p><ul><li><p>TRANSACTION_NONE - informs that the driver does not support transactions;</p></li><li><p>TRANSACTION_READ_UNCOMMITTED - allows transactions to see uncommitted data changes, which allows dirty, non-repeatable, and phantom reads;</p></li><li><p>TRANSACTION_READ_COMMITTED - means that any change made to the transaction is not visible outside of it until it is saved. This prevents dirty reads, but allows non-repeatable and phantom reads;</p></li><li><p>TRANSACTION_REPEATABLE_READ - disables dirty and non-repeating reads, but phantom reads are allowed;</p></li><li><p>TRANSACTION_SERIALIZABLE Specifies that dirty, non-repeatable, and phantom reads are disabled.</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE THE TYPES OF READING TRANSACTIONS ERRORS?</strong></p></li></ul><p><br></p><p>There are several types of reading for transactions errors. They are:</p><ul><li><p><strong>dirty reads</strong> occur when transactions are allowed to see unsaved data changes. In other words, changes made in one transaction are visible outside of it before it was saved. If the changes are not saved, then it is likely that other transactions were doing work based on incorrect data;</p></li><li><p><strong>nonrepeatable reads</strong> occur when transaction A reads a row, transaction B modifies that row, transaction A reads the same row and receives the updated data;</p></li></ul><p><strong>phantom reads</strong> occur when transaction A reads all rows that satisfy the WHERE condition, transaction B inserts a new row or deletes one of the rows that satisfies this condition, transaction A reads all the rows that satisfy the WHERE condition together again with a new line or missing the old one.</p></div>
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+                <div class="heading">Part 2 Databases - Questions and Answers</div>
+                <div class="article-asset-container"><ul><li><p><strong>WHAT IS A DATABASE?</strong></p></li></ul><p><br></p><p>A database (DB) is an organized set of information. As an example of the simplest database, we can give a list of goods, each of which has a set of standard characteristics (name, unit of measure, quantity, price, etc.).</p><p><br></p><p>Usually, when we speak about databases we mean some specific persistence storage.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS A DATA MODEL IN RELATIONAL DBMS?</strong></p></li></ul><p><br></p><p>Before storing any data in the DBMS, it is necessary to describe their model. According to the type of data model, DBMS are divided into network, object, hierarchical and relational. Relational type DBMS are the most common and frequently used. Examples include Oracle, MySQL, Microsoft SQL Server and others.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS NORMALIZATION?</strong></p></li></ul><p><br></p><p>The process of bringing a database into a form in which it will conform to the rules of normal forms is called database normalization. Database normalization minimizes the amount of redundant information. Its purpose is to save data only once, but in the right place.</p><p><br></p><p>A normalized database eliminates data duplication and multiple maintenance, as well as data integrity issues that arise when the same data is entered repeatedly. Initially, only 3 normal forms were defined by Dr. Edgar Codd. Further development of relational theory led to the emergence of several more forms, and at the moment there are 8 of them. In practice, the compliance of the database with the rules of the 3rd normal form is quite enough.</p><p><br></p><p>First normal form states that the information in each field of a table is atomic and cannot be subdivided.</p><p><br></p><p>The second normal form states that the table is in 1NF and there are no non-key attributes in the table that depend on part of a complex (multi-column) primary key.</p><p><br></p><p>The third normal form states that the table corresponds to the first two NFs, and all non-key attributes depend only on the primary key and are independent of each other.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE THE TYPES OF RELATIONS IN THE DATABASE. GIVE AN EXAMPLE</strong></p></li></ul><p><br></p><p>Linking works by matching data in key columns; usually these are columns with the same name in both tables. In most cases, a relationship maps the primary key of one table, which is the unique identifier for each row in that table, to the foreign key entries of another table.</p><p><br></p><p>There are three types of relationships between tables. The type of relationship that is created depends on how the related columns are defined.</p><p><br></p><p><strong>One-to-one</strong> - in a one-to-one relationship, only one row in table B can match a row in table A, and vice versa. A one-to-one relationship is created if both related keys have primary key or unique constraints defined.</p><p><br></p><p>This type of relationship is usually not used because most of the data related in this way can be stored in a single table. A one-to-one relationship can be used to:</p><ul><li><p>Splitting a table with many columns.</p></li><li><p>Isolate part of the table for security reasons.</p></li><li><p>Storage of short-term data that can be easily deleted along with the entire table.</p></li><li><p>Storing data that only applies to part of the main table.</p></li></ul><p><br></p><p>The column that is the primary key in a one-to-one relationship is marked with a key symbol. A column that is a foreign key is also marked with a key symbol.</p><p><br></p><p><strong>One-to-many</strong> is the most common. In this type of relationship, a row of table A can have multiple matching rows of table B, but each row of table B can match only one row from A. For example, there is a one-to-many relationship between the publishers and books tables: each publisher publishes many books, but each book is published by only one publisher.</p><p>Use a one-to-many relationship if only one of the related columns has a primary key or unique constraint.</p><p><br></p><p>The column that is the primary key in a one-to-many relationship is marked with a key symbol. A column that is a foreign key in a one-to-many relationship is marked with an infinity symbol.</p><p><br></p><p><strong>Many-to-Many</strong> - A row in Table A can match multiple rows in Table B, and vice versa. Such relationships are created by defining a third table, called the join table, whose primary key consists of foreign keys A and B. <br><br></p><p>Such relationships are created by defining a third table, called the join table, whose primary key consists of foreign keys A and B. For example, the many-to-many relationship between the authors and books tables is defined through the one-to-many relationships of each of these tables to the books_authors table. The primary key of the books_authors table is a combination of the au_id column (the primary key of the authors table) and the book_id column (the primary key of the titles table).</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS A PRIMARY KEY?</strong></p></li></ul><p><br></p><p>Primary key (or master key, primary key, PK) represents a column or collection of columns whose values uniquely identify rows.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS FOREIGN KEY?</strong></p></li></ul><p><br></p><p>Secondary (or foreign key, foreign key, FK) is a column or set of columns that is not a primary key in this table but is a primary key in another table. Foreign key is used to establish a logical relationship between the table rows and the corresponding rows in the another table.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE INDEXES IN A DATABASE? WHAT ARE THEY USED FOR? WHAT IS GOOD IN USING THEM AND WHAT IS BAD?</strong></p></li></ul><p><br></p><p>Indexes are special structures in databases that allow you to speed up searching and sorting by a specific field or set of fields in a table, and are also used to ensure the uniqueness of data. The easiest way to compare indexes is with indexes in books. If there is no pointer, then we will have to look through the entire book to find the right place, and with a pointer, the same action can be performed much faster.</p><p><br></p><p>Typically, the more indexes, the better the performance of database queries. However, with an excessive increase in the number of indexes, the performance of data modification operations (insert/modify/delete) decreases, the size of the database increases, so adding indexes should be treated with caution.</p><p><br></p><p>Some general principles related to creating indexes:</p><ul><li><p>indexes need to be created for columns that are used in joins that are often searched and sorted. It should be noted that indexes are always automatically created for columns that are subject to the primary key constraint. Most often they are also created for columns with a foreign key;</p></li><li><p>an index is necessarily automatically created for columns that have a unique constraint;</p></li><li><p>it is best to create indexes for those fields in which - the minimum number of duplicate values and the data is evenly distributed. Oracle has special bitwise indexes for columns with a large number of duplicate values, SQL Server doesn’t provide this kind of index;</p></li><li><p>if the search is constantly performed on a certain set of columns (simultaneously), then in this case it may make sense to create a composite index (only in SQL Server) - one index for a group of columns;</p></li><li><p>when changes are made to tables, the indexes imposed on this table are automatically changed. As a result, the index can be highly fragmented, which affects performance. Indexes should be periodically checked for fragmentation and defragmented. When loading a large amount of data, it sometimes makes sense to first remove all indexes, and after the operation is completed, create them again;</p></li><li><p>Indexes can be created not only for tables, but also for views (only in SQL Server). Advantages - the ability to calculate fields not at the time of the request, but at the time of the appearance of new values in the tables.</p></li></ul><p><br></p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE THE INDEX TYPES?</strong></p></li></ul><p><br></p><p>Four types of indexes can be created in the database, depending on its functionality: unique, clustered, full-text and primary key index.</p><ul><li><p>Unique index - An index is unique if there cannot be two rows with the same index value. Most databases will not allow a table to be stored with a unique index created on it if there are duplicate key values in the existing data. The database may also be prohibited from adding new data that results in duplicate key values in the table. For example, if you create a unique index on the employee's last name on the employee table, there should not be two employees with the same last name.</p></li><li><p>Primary Key Index - A database table typically has a column or combination of columns whose values uniquely identify each row in the table. Such a column is called the primary key of the table. Defining a primary key for a table in a database schema automatically creates a primary key index, which is a kind of unique index. This index requires each value of the primary key to be unique. It also provides fast data access when using a primary key index in queries.</p></li><li><p>Clustered index - in a clustered index, the physical order of the rows in the table is the same as the logical (indexed) order of the key values. A table can have only one clustered index. If the index is not clustered, the physical order of the table rows is different from the logical order of the key values. A clustered index generally provides faster data access than other indexes.</p></li><li><p>Full-text index - a full-text index is created if you want to perform a full-text search on the text columns of database tables. The full-text index depends on the regular index, so you'll need to create one first. A regular index should be created on a single non-nullable column, and it's best to choose columns with small values rather than large ones.</p></li></ul><p><br></p><p><br></p></div>
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+                border: 1px solid #d1d7dc;
+                color: #b4690e;
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+                <div class="heading">Part 3 SQL - Questions and Answers</div>
+                <div class="article-asset-container"><ul><li><p><strong>WHAT IS SQL?</strong></p></li></ul><p><br></p><p>SQL (structured query language) is a formal query language used to create, modify and manage data in an arbitrary relational database managed by an appropriate database management system (DBMS). SQL is based on the tuple calculus.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE THE TYPES OF JOIN? BRIEFLY DESCRIBE EACH TYPE</strong></p></li></ul><p><br></p><p>(INNER) JOIN - inner join. The result set contains only records that have the same related field values.</p><p><br></p><p>LEFT JOIN - left outer join. The result set contains all records from Table1 and their corresponding records from Table2. If there is no match, the fields from Table2 will be empty.</p><p><br></p><p>RIGHT JOIN - right outer join. The result set contains all records from Table2 and their corresponding records from Table1. If there is no match, the fields from Table1 will be empty.</p><p><br></p><p>FULL JOIN - full outer join. A combination of the previous two. The result set contains all records from Table1 and their corresponding records from Table2. If there is no match, the fields from Table2 will be empty. Records from Table2 that did not find a match in Table1 will also be present in the result set. In this case, the fields from Table1 will be empty.</p><p><br></p><p>CROSS JOIN - Cartesian product. The result set contains all combinations of rows from Table1 and Table2. The connection condition is not specified.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE WORD HAVING USED FOR?</strong></p></li></ul><p><br></p><p>The HAVING section defines a condition that is then applied to groups of strings. Therefore, this clause has the same meaning for a group of rows as the WHERE clause has for the contents of the corresponding table. Syntax of the HAVING clause:</p><p><br></p><ul><li><p>HAVING condition</p></li></ul><p><br></p><p>where condition contains aggregate functions or constants.</p><p><br></p><p>It is important to understand that the HAVING and WHERE clauses complement each other. First, with the help of WHERE constraints, the final selection is formed, then the breakdown into groups is performed according to the values of the fields specified in GROUP BY. Further, for each group, the group function is calculated and, finally, the HAVING condition is imposed.</p><p><br></p><p>SELECT DeptNum, MAX(SALARY) FROM Employees GROUP BY DeptNum HAVING MAX(SALARY) &gt; 1000</p><p>In the above example, only departments with a maximum salary greater than 1000 will be included in the result.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS DDL?</strong></p></li></ul><p><br></p><p>DDL(Data Definition Language) - Commands for defining the data structure. The DDL group includes commands that allow you to define the internal structure of the database. Before you save data in the database, you need to create tables in it and, possibly, some other related objects.</p><p><br></p><p>For example:</p><ul><li><p>CREATE TABLE</p></li><li><p>DROP TABLE</p></li><li><p>ALTER TABLE</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT IS DML?</strong></p></li></ul><p><br></p><p>DML(Data Manipulation Language) - Data manipulation commands. The DML group contains commands that allow you to enter, modify, delete, and retrieve data from tables.</p><p><br></p><p>Examples of DML commands:</p><ul><li><p>SELECT</p></li><li><p>INSERT</p></li><li><p>UPDATE</p></li><li><p>DELETE</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT IS TCL?</strong></p></li></ul><p><br></p><p>TCL(Transaction Control Language) - TCL commands are used to manage data changes produced by DML commands. With their help, several DML commands can be combined into a single logical entity, called a transaction.</p><p><br></p><p>In this case, all commands for changing data within one transaction either complete successfully, or all can be canceled in case of any problems with the execution of any of them.</p><p><br></p><p>TCL commands examples:</p><ul><li><p>COMMIT</p></li><li><p>ROLLBACK</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT IS DCL?</strong></p></li></ul><p><br></p><p>DCL(Data Control Language) - Access control commands. DCL commands control user access to the database and individual objects:</p><ul><li><p>GRANT</p></li><li><p>REVOKE</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>ABOUT NULL IN SQL.</strong></p></li></ul><p><br></p><p>It should be noted that the SQL language, unlike programming languages, has built-in tools to support the absence of any data. This is done using the NULL concept. NULL is not some fixed value stored in a record field instead of the actual data. The NULL value has no defined type. NULL is an indicator that tells the user (and SQL) that there is no data in the record field. Therefore, it cannot be used in comparison operations. To check the fact of the presence or absence of data in SQL, special expressions are introduced.</p><p><br></p><p><br></p><ul><li><p><strong>IF YOU ARE GOING TO JOIN MULTIPLE TABLES IN A QUERY (FOR EXAMPLE N TABLES), HOW MANY JOIN CONDITIONS SHOULD YOU USE?</strong></p></li></ul><p><br></p><p>Then you need to use n-1 join conditions to eliminate the Cartesian join, it may be that more than n-1 join conditions are needed, and completely different join conditions to further reduce the resulting dataset.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE PRACTICAL USE OF TEMPORARY TABLES?</strong></p></li></ul><p><br></p><p>A temporary table is a database object that is stored and managed by the database system on a temporary basis. They can be local or global. They are used to store the results of a stored procedure call, reduce the number of rows on joins, aggregate data from different sources, or replace cursors and parameterized views.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>HOW DOES THE GROUP BY STATEMENT TREAT A NULL VALUE? IS IT A GENERAL INTERPRETATION OF SUCH VALUES?</strong></p></li></ul><p><br></p><p>When using GROUP BY, all NULL values are considered equal. The NULL value is a special value that can be assigned to a table cell. This value is typically used when the information in a cell is unknown or inappropriate.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE DIFFERENCE BETWEEN COUNT(*) AND COUNT(COLUMN)?</strong></p></li></ul><p><br></p><p>The form COUNT(column) counts the number of values in "column". This form of the COUNT function does not take NULL into account when counting the number of values in a column. the COUNT(*) function counts the number of rows in a table, does not ignore NULL, since this function operates on rows, not columns.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE DIFFERENCE BETWEEN DISTINCT AND GROUP BY OPERATORS?</strong></p></li></ul><p><br></p><p>DISTINCT Specifies that only unique values in the column are used for calculations. NULL is treated as a single value. If you need to remove only duplicates, it is better to use DISTINCT.</p><p><br></p><p>GROUP BY groups the selected set of rows to produce a set of summary rows based on the values of one or more columns or expressions. GROUP BY creates a separate group for all possible values (including null). GROUP BY is best used to define groups of output rows to which aggregate functions (COUNT, MIN, MAX, AVG, and SUM) can be applied.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE UNION, INTERSECT, EXCEPT OPERATORS FOR?</strong></p></li></ul><p><br></p><p>The UNION operator is used to combine the results of two SQL queries into a single table consisting of similar terms. Both queries must return the same number of columns and compatible data types in the respective columns.</p><p><br></p><p>The INTERSECT operator is used to find the intersection of two sets. The result of its execution will be a set of strings that are present in both sets.</p><p><br></p><p>The EXCEPT operator is used to find the difference of two sets. The result of the execution is a set of rows from set 1 that are not in set 2.</p><p><br></p><p>Execution precedence of operators on sets:</p><p>INTERSECT -&gt; EXCEPT -&gt; UNION</p><p><br></p><p><br></p><ul><li><p><strong>WHICH IS BETTER TO USE JOIN OR SUBQUERY?</strong></p></li></ul><p><br></p><p>It's usually better to use JOIN because it's understandable in most cases and is better optimized by the Database Engine. but not always. Joins take precedence over subqueries when the SELECT query contains columns from more than one table.</p><p><br></p><p>Subqueries are best when you need to calculate an aggregate value and use them in outer queries for comparisons.</p><p><br></p></div>
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+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
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+                height: 100%;
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+                padding: 3.2rem 4.8rem;
+                word-break: break-word;
+                max-width: 69.6rem;
+                margin: 0 auto;
+            }
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+                <div class="heading">Part 4 SQL - Questions and Answers</div>
+                <div class="article-asset-container"><ul><li><p><strong>WHAT DOES THE EXISTS FUNCTION DO?</strong></p></li></ul><p><br></p><p>The EXISTS function argument is an inner query. It returns true if the query returns one or more rows, and returns false if the query returns zero rows.</p><p><br></p><p><br></p><ul><li><p><strong>USING THE PIVOT OPERATOR.</strong></p></li></ul><p><br></p><p>The PIVOT relational operator can be used to modify a table-valued expression in another table. The PIVOT operator expands a table-valued expression, transforming the unique values of one column of the expression into multiple output columns, and optionally concatenates the remaining duplicate column values and displays them in the output.</p><p><br></p><p><br></p><ul><li><p><strong>DESCRIBE THE DIFFERENCE OF THE DATETIME AND TIMESTAMP DATA TYPES.</strong></p></li></ul><p><br></p><p>DATETIME is intended to store an integer: YYYYMMDDHHMMSS. And this time does not depend on the time zone configured on the server. Stores: 8 bytes</p><p><br></p><p>TIMESTAMP stores a value equal to the number of seconds that have passed since midnight on January 1, 1970 GMT. When received from the database, it is displayed taking into account the time zone. Stores: 4 bytes.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>FOR WHAT NUMERICAL TYPES IS IT UNACCEPTABLE TO USE THE OPERATION OF ADDITION (Subtraction), AND THEREFORE THE FUNCTION SUM ()?</strong></p></li></ul><p>As operands of addition and subtraction operations, any valid expression of any data type of the numeric category is allowed, except for the bit data type.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE STORED PROCEDURES?</strong></p></li></ul><p><br></p><p>A stored procedure is a compiled set of SQL statements that is part of the database and stored on the server. There is a lot in common between Stored Procedures and ordinary programming language procedures: they can have input parameters and output results, they can perform various numerical calculations, as well as perform standard database operations. As with procedures in other programming languages, they can have loops and branches.</p><p><br></p><p><br></p><ul><li><p><strong>RANKING FUNCTIONS: WHAT IS IT AND WHICH EXISTS?</strong></p></li></ul><p><br></p><p>The ranking functions return a ranking value for each row in a partition. Depending on the function used, the values of some strings may be the same. The ranking functions are non-deterministic.</p><p>Transact-SQL contains the following ranking functions:</p><ul><li><p>RANK</p></li><li><p>NTILE</p></li><li><p>DENSE_RANK</p></li><li><p>ROW_NUMBER</p></li></ul><p><br></p><p>Syntax:<br><br>SELECT column_name</p><p>RANK() OVER (</p><p>PARTITION BY expression</p><p>ORDER BY expression [ASC|DESC])</p><p>AS 'my_rank' FROM table_name;</p><p><br></p><p>In this syntax,</p><p><br></p><ul><li><p>The OVER clause sets the partitioning and ordering of a result before the associated window function is applied.</p></li><li><p>The PARTITION BY clause divides the output produces by the FROM clause into the partition. Then the function is applied to each partition and re-initialized when the division border crosses partitions. If we have not defined this clause, the function will treat all rows as a single partition.</p></li><li><p>The ORDER BY is a required clause that determines the order of the rows in a descending or ascending manner based on one or more column names before the function is applied.</p></li></ul><p><br></p><p><br></p><p>Example:</p><p><br></p><p>SELECT first_name, last_name, city,</p><p>RANK () OVER (ORDER BY city) AS Rank_No</p><p>FROM rank_demo;</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>CAN A VALUE IN A COLUMN WITH A FOREIGN KEY CONSTRAINTS BE NULL?</strong></p></li></ul><p><br></p><p>Yes, it can. If this column is not constrained not null, example: when building a file system tree table, where the foreign key column is a link to the same table, to a tuple with information about the parent directory, then for the root directory of the file system in the parent column directory will be null.</p><p><br></p><p><br></p><ul><li><p><strong>NAME THE MAIN PROPERTIES OF A TRANSACTION.</strong></p></li></ul><p><br></p><p>ACID - atomicity, consistency, isolation, durability.</p><p><br></p><p>The <strong>atomicity </strong>property guarantees the indivisibility of a set of statements that modify data in the database and are part of a transaction. This means that either all data changes in the transaction are performed, or in case of any error, all changes already made are canceled.</p><p><br></p><p><strong>Consistency </strong>ensures that the transaction does not allow the database to contain inconsistent data. In other words, data transformation within a single transaction moves the database from one consistent state to another consistent state.</p><p><br></p><p>The <strong>isolation </strong>property separates all concurrently executing transactions. In other words, no active transaction can see data changes made in a concurrent but not completed transaction. This means that some transactions can be rolled back to provide isolation.</p><p><br></p><p><strong>Durability </strong>- after its completion, the transaction is stored in the system, which nothing can return to its original (before the start of the transaction) state, i.e. the transaction is committed, meaning that its effect is permanent even if the system fails.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>HOW TO DELETE REPEATED ROWS USING THE DISTINCT KEYWORD?</strong></p></li></ul><p><br></p><p>SELECT DISTINCT columnsName FROM tableName;</p><p><br></p><p>where: columnsName - one or more real names of columns separated by commas; tableName is the name of the table from which these columns are selected.</p><p><br></p><p>If more than one column is included in the SELECT DISTINCT clause, then the uniqueness of any row will be determined by the uniqueness of the corresponding combination of all column values included in the clause on that same row among similar combinations matching other rows.</p><p>Although null values are never equal to each other (because they are considered unknown), the DISTINCT clause, on the contrary, considers them duplicates. Therefore, the SELECT DISTINCT command will return only one null value, no matter how many null values it encounters.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHEN IS A FULL TABLE SCAN BETTER THAN INDEX ACCESS? SHORTLY DESCRIBE THE GENERAL PRINCIPLES OF HOW THE OPTIMIZER CHOOSE WHETHER TO DO A FULL TABLE SCAN OR ACCESS BY INDEX.</strong></p></li></ul><p><br></p><p>A full scan is performed by a multi-block read. Scanning by index - single-block. Also, when accessing by index, the index itself is scanned first, and then blocks are read from the table.</p><p><br></p><p>The number of blocks that must be read from the table depends on the clustering factor.</p><p>If the total cost of all required single-block reads is greater than the cost of a full scan by multi-block reads, then a full scan is more profitable and is chosen by the optimizer. Thus, a full scan is chosen when the overgrowth predicate selectivity and/or data clustering is weak, or in the case of very small tables.</p><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS AN AGGREGATE FUNCTION? GIVE EXAMPLES OF AGGREGATE FUNCTIONS IN SQL.</strong></p></li></ul><p><br></p><p>An aggregate function is a function that returns a single value based on multiple records.</p><p>Here is a list of some SQL aggregate functions:</p><ul><li><p>COUNT(*) - Returns the number of rows in the record source</p></li><li><p>COUNT - Returns the number of values in the specified column</p></li><li><p>SUM - Returns the sum of the values in the specified column</p></li><li><p>AVG - Returns the average value in the specified column</p></li><li><p>MIN - Returns the minimum value in the specified column</p></li><li><p>MAX - Returns the maximum value in the specified column</p></li></ul><p><br></p><p><br></p><p><br></p><ul><li><p><strong>DEFINE THE THIRD NORMAL FORM OF THE DB.</strong></p></li></ul><p><br></p><p>Definition of the third normal form of a database.</p><ul><li><p>Any field of any record stores only one value. (1NF) For example, if a field contains a comma-separated list of identifiers, then this is a violation of this definition.</p></li><li><p>The 1NF condition is met and any non-key field is completely dependent on the key (2NF). For example, we have a record with fields (Identifier, CD Name, Group Name), where the key is the "Identifier" field. At the same time, it is obvious that the "Group Name" field depends not only on the "Identifier" but also on the "CD-Disk Name" field. Therefore, such a database is not in second normal form.</p></li><li><p>The 2NF condition is met and there are no non-key fields dependent on the value of other non-key fields. For example, we store the region code and its name in the record. It is clear that the name of the region depends on the code, and vice versa, so such a database will not be in the third normal form.</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT IS DB DENORMALIZATION? WHAT DOES IT NEED FOR?</strong></p></li></ul><p><br></p><p>Denormalization is the process of deliberately making a database appear in a way that does not conform to the rules of normalization. This is sometimes necessary to improve performance and data retrieval speed by increasing data redundancy.</p><p><br></p><p>If an application needs to frequently perform selects that take too long (for example, joining data from many tables), then denormalization should be considered.</p><p><br></p><p>A possible solution is the following: put the results of the sample in a separate table. This will speed up queries, but it also means that this new table needs constant maintenance. Before proceeding with denormalization, you need to make sure that the expected results justify the costs that you have to face.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS A TRIGGER?</strong></p></li></ul><p><br></p><p>A trigger is a SQL procedure that fires on some event (INSERT, DELETE or UPDATE). Triggers are stored and managed by the DBMS. Triggers are used to maintain the referential integrity of data in the same manner by responding to data change events. The trigger cannot be called or executed manually, the DBMS automatically calls it after modifying the data in the corresponding table. This is where it differs from stored procedures, which must be executed manually by calling CALL. A trigger can also call other procedures.</p><p><br></p><p>A trigger can also contain INSERT, DELETE, and UPDATE calls within itself, thus calling another trigger. Such triggers are called nested.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT ARE CURSORS IN DATABASES?</strong></p></li></ul><p><br></p><p>In computer science, a database cursor is a mechanism that enables traversal over the records in a database. Cursors facilitate subsequent processing in conjunction with the traversal, such as retrieval, addition and removal of database records. The database cursor characteristic of traversal makes cursors akin to the programming language concept of iterator.</p><p><br></p><p>Cursors are used by database programmers to process individual rows returned by database system queries. Cursors enable manipulation of whole result sets at once. In this scenario, a cursor enables the sequential processing of rows in a result set.</p><p><br></p><p>In SQL procedures, a cursor makes it possible to define a result set (a set of data rows) and perform complex logic on a row by row basis. By using the same mechanics, a SQL procedure can also define a result set and return it directly to the caller of the SQL procedure or to a client application.</p><p><br></p><p>A cursor can be viewed as a pointer to one row in a set of rows. The cursor can only reference one row at a time, but can move to other rows of the result set as needed.</p><p><br></p><p>A cursor is a database object that allows applications to work with records "one at a time", rather than many at once, as it is done in regular SQL commands.</p><p><br></p><p>The procedure for working with a cursor is as follows:</p><ul><li><p>Define Cursor (DECLARE)</p></li><li><p>Open Cursor (OPEN)</p></li><li><p>Get record from cursor (FETCH)</p></li><li><p>Process entry</p></li><li><p>Close cursor (CLOSE)</p></li></ul><p><br></p><p><br></p><p><br></p><ul><li><p><strong>WHAT COMPROMISES DOES THE USE OF INDICES OFFER?</strong></p></li></ul><p><br></p><p>Some of them:</p><ul><li><p>Faster fetches but slower changes. (Changes take time to rebuild the index).</p></li><li><p>Indexes require additional disk space.</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT DOES THE SQL MERGE OPERATION DO?</strong></p></li></ul><p><br></p><p>The MERGE operation has officially appeared in the ANSI SQL:2008 standard.</p><p>It allows you to insert or modify table records at the same time according to the criteria. When the criterion is met, the rows are changed, otherwise they are inserted. It can be replaced by sequential calls to INSERT and UPDATE. In some databases, a similar operation is called UPSERT.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE DIFFERENCE BETWEEN THE HAVING AND WHERE EXPRESSIONS?</strong></p></li></ul><p><br></p><p>WHERE is a limiting expression. It is executed before the result of the operation is received.</p><p>HAVING is a filter expression. It is applied to the result of the operation and is executed after this result is received, unlike where.</p><p>WHERE clauses are used with SELECT, UPDATE, DELETE statements, while HAVING clauses are used only with SELECT and GROUP BY clause.</p><p><br></p><p>That is, it is impossible to use WHERE in queries with aggregate functions, and HAVING was introduced for this.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS DATA INTEGRITY? EXPLAIN WHAT THE LIMITS ARE.</strong></p></li></ul><p><br></p><p>Data integrity is an important property of SQL. When used correctly, it ensures the correctness and validity of the stored data at any given time. Also, they can be used to detect errors in applications that are difficult to find in other ways. Data integrity is maintained through constraints.</p><p>There are 4 main restrictions in ANSI SQL: PRIMARY KEY, CHECK, UNIQUE and FOREIGN KEY. They are not required for the table.</p><p><br></p><ul><li><p>PRIMARY KEY - a set of fields (1 or more) whose values form a unique combination and are used to uniquely identify a record in a table. Only one such constraint can be created for a table. This constraint is used to ensure the integrity of the entity described by the table.</p></li><li><p>CHECK is used to restrict the set of values that can be placed in a given column. This constraint is used to ensure the integrity of the subject area that the tables in the database describe.</p></li><li><p>A UNIQUE constraint ensures that there are no duplicates in a column or set of columns. The difference between PRIMARY KEY and UNIQUE is described in primary and unique keys, in the question below.</p></li><li><p>A FOREIGN KEY constraint protects against actions that can break relationships between tables. FOREIGN KEY in one table points to PRIMARY KEY in another. Therefore, this restriction is intended to ensure that there are no FOREIGN KEY entries that do not match the PRIMARY KEY entries. Thus, FOREIGN KEY maintains the referential integrity of the data.</p></li></ul><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE DIFFERENCE BETWEEN PRIMARY AND UNIQUE CONSTRAINTS?</strong></p></li></ul><p><br></p><p>The primary and unique constraints are designed to ensure that the values of the column on which they are defined are unique. But by default, the primary constraint creates a clustered index on the column, while the unique constraint creates a non-clustered one. Another difference is that primary does not allow NULL entries, while unique only allows one NULL entry.</p><p><br></p><p><br></p><ul><li><p><strong>WHAT IS THE DIFFERENCE BETWEEN CLUSTER AND NON-CLUSTER INDEXES?</strong></p></li></ul><p><br></p><p>Non-clustered indexes are created by the DBMS by default. The data is physically random, but logically ordered according to the index. This type of index is suitable for tables where values change frequently.</p><p><br></p><p>With clustered indexing, the data is physically ordered, which greatly increases the speed of data retrieval (but only in the case of sequential data access). Only one clustered index can be created per table.</p><p><br></p></div>
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