| # Task: 009 |
|
|
| **Database:** retails |
|
|
| ## Question |
| List the customer who made the highest number of purchases using rail shipping. |
|
|
|
|
| ## Gold Query |
|
|
| ```sql |
| WITH customer_rail_lineitems AS ( |
| SELECT c.c_custkey, |
| c.c_name, |
| COUNT(*) AS rail_ship_count |
| FROM customer c |
| JOIN orders o ON c.c_custkey = o.o_custkey |
| JOIN lineitem l ON o.o_orderkey = l.l_orderkey |
| WHERE l.l_shipmode = 'RAIL' |
| GROUP BY c.c_custkey, c.c_name |
| ) |
| SELECT c.c_custkey, c.c_name, c.rail_ship_count |
| FROM customer_rail_lineitems c |
| WHERE c.rail_ship_count = ( |
| SELECT MAX(rail_ship_count) FROM customer_rail_lineitems |
| ); |
| ``` |
|
|
| **Execution Result:** |
|
|
| | c_custkey | c_name | rail_ship_count | |
| |-------------|--------------------|-------------------| |
| | 63035 | Customer#000063035 | 28 | |
|
|
| *1 rows* |
