File size: 4,548 Bytes
19dfd32
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
use employee;

delimiter //
drop function if exists emp_dept_id //
drop function if exists emp_dept_name //
drop function if exists emp_name //
drop function if exists current_manager //
drop procedure if exists show_department //

--
-- returns the department id of a given employee
--
create function emp_dept_id( employee_id int )
returns char(4)
reads sql data
begin
    declare max_date date;
    set max_date = (
        select
            max(from_date)
        from
            dept_emp
        where
            emp_no = employee_id
    );
    set @max_date=max_date;
    return (
        select
            dept_no
        from
            dept_emp
        where
            emp_no = employee_id
            and
            from_date = max_date
            limit 1
    );
end //

--
-- returns the department name of a given employee
--

create function emp_dept_name( employee_id int )
returns varchar(40)
reads sql data
begin
    return (
        select
            dept_name
        from
            department
        where
            dept_no = emp_dept_id(employee_id)
    );
end//

--
-- returns the employee name of a given employee id
--
create function emp_name (employee_id int)
returns varchar(32)
reads SQL data
begin
    return (
        select
            concat(first_name, ' ', last_name) as name
        from
            employee
        where
            emp_no = employee_id
    );
end//

--
-- returns the manager of a department
-- choosing the most recent one
-- from the manager list
--
create function current_manager( dept_id char(4) )
returns varchar(32)
reads sql data
begin
    declare max_date date;
    set max_date = (
        select
            max(from_date)
        from
            dept_manager
        where
            dept_no = dept_id
    );
    set @max_date=max_date;
    return (
        select
            emp_name(emp_no)
        from
            dept_manager
        where
            dept_no = dept_id
            and
            from_date = max_date
            limit 1
    );
end //

delimiter ;

--
--  selects the employee records with the
--  latest department
--

CREATE OR REPLACE VIEW  v_full_employee
AS
SELECT
    emp_no,
    first_name , last_name ,
    birth_date , gender,
    hire_date,
    emp_dept_name(emp_no) as department
from
    employee;

--
-- selects the department list with manager names
--

CREATE OR REPLACE VIEW v_full_department
AS
SELECT
    dept_no, dept_name, current_manager(dept_no) as manager
FROM
    department;

delimiter //

--
-- shows the department with the number of employee
-- per department
--
create procedure show_department()
modifies sql data
begin
    DROP TABLE IF EXISTS department_max_date;
    DROP TABLE IF EXISTS department_people;
    CREATE TEMPORARY TABLE department_max_date
    (
        emp_no int not null primary key,
        dept_from_date date not null,
        dept_to_date  date not null, # bug#320513
        KEY (dept_from_date, dept_to_date)
    );
    INSERT INTO department_max_date
    SELECT
        emp_no, max(from_date), max(to_date)
    FROM
        dept_emp
    GROUP BY
        emp_no;

    CREATE TEMPORARY TABLE department_people
    (
        emp_no int not null,
        dept_no char(4) not null,
        primary key (emp_no, dept_no)
    );

    insert into department_people
    select dmd.emp_no, dept_no
    from
        department_max_date dmd
        inner join dept_emp de
            on dmd.dept_from_date=de.from_date
            and dmd.dept_to_date=de.to_date
            and dmd.emp_no=de.emp_no;
    SELECT
        dept_no,dept_name,manager, count(*)
        from v_full_department
            inner join department_people using (dept_no)
        group by dept_no;
        # with rollup;
    DROP TABLE department_max_date;
    DROP TABLE department_people;
end //

drop function if exists employee_usage //
drop procedure if exists employee_help //

CREATE FUNCTION employee_usage ()
RETURNS TEXT
DETERMINISTIC
BEGIN
    RETURN
'
    == USAGE ==
    ====================

    PROCEDURE show_department()

        shows the department with the manager and
        number of employee per department

    FUNCTION current_manager (dept_id)

        Shows who is the manager of a given departmennt

    FUNCTION emp_name (emp_id)

        Shows name and surname of a given employee

    FUNCTION emp_dept_id (emp_id)

        Shows the current department of given employee
';
END //

create procedure employee_help()
deterministic
begin
    select employee_usage() as info;
end//

delimiter ;