| # Task: 017 |
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| **Database:** retails |
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|
| ## Question |
| Find the customer with the largest order value in each market segment. |
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| ## Gold Query |
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|
| ```sql |
| WITH order_totals AS ( |
| SELECT c_mktsegment, c.c_custkey, c.c_name, SUM(o.o_totalprice) AS total_o_totalprice |
| FROM customer c |
| JOIN orders o ON c.c_custkey = o.o_custkey |
| GROUP BY c_mktsegment, c.c_custkey, c.c_name |
| ) |
| SELECT |
| ot.c_mktsegment AS market_segment, |
| ot.c_custkey AS customer_key, |
| ot.c_name AS customer_name, |
| ot.total_o_totalprice AS largest_value |
| FROM order_totals ot |
| JOIN ( |
| SELECT ot2.c_mktsegment, MAX(ot2.total_o_totalprice) AS max_value |
| FROM order_totals ot2 |
| GROUP BY ot2.c_mktsegment |
| ) AS max_val ON ot.c_mktsegment = max_val.c_mktsegment AND ot.total_o_totalprice = max_val.max_value; |
| ``` |
|
|
| **Execution Result:** |
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|
| | market_segment | customer_key | customer_name | largest_value | |
| |------------------|----------------|--------------------|-----------------| |
| | AUTOMOBILE | 114308 | Customer#000114308 | 5486668.8 | |
| | BUILDING | 58421 | Customer#000058421 | 5487155.8 | |
| | FURNITURE | 41290 | Customer#000041290 | 5473361.7 | |
| | HOUSEHOLD | 79933 | Customer#000079933 | 5928489.4 | |
| | MACHINERY | 58387 | Customer#000058387 | 5719569.4 | |
|
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| *5 rows* |
