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Deduplicate Orders with ROW_NUMBER
Some customers placed multiple orders for the same product on the same date. Deduplicate by keeping only the order with the highest total for each (customer_id, product, order_date) combination. Show order_id, customer_id, product, order_date, and total. Sort by customer_id, order_date. This deduplication pattern with ROW_NUMBER is a top-5 FAANG SQL question.
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Schema
orders
| order_id | customer_id | product | category | quantity | price | total | order_date | country | status |
|---|---|---|---|---|---|---|---|---|---|
| 1 | 1 | Laptop Pro | Electronics | 1 | 1299.99 | 1299.99 | 2024-01-15 | USA | completed |
| 2 | 2 | Wireless Mouse | Electronics | 2 | 49.99 | 99.98 | 2024-01-16 | Canada | completed |
| 3 | 3 | Office Chair | Furniture | 1 | 349.99 | 349.99 | 2024-01-17 | USA | completed |
Expected output: Keep only the $999 order
Hint
Concepts
SELECT Window Functions ROW_NUMBER PARTITION BY CTE Window Functions + CTE
Practise the topic: SQL practice questions · Window function practice · CTE practice · Ranking function practice · Advanced SQL interview questions
Read the concept: ROW_NUMBER vs RANK vs DENSE_RANK
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