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Top-N Products per Category
Find the top 2 best-selling products (by total quantity sold) in each category. Show category, product, total_qty (sum of quantity), and category_rank. If a category has fewer than 2 products, show all of them. Sort by category, category_rank. Top-N per group is one of the most frequently asked FAANG SQL patterns because it combines window functions with filtering on derived columns.
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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: Laptop rank 1, Phone rank 2
Hint
Concepts
SELECT CTE Window Functions ROW_NUMBER PARTITION BY GROUP BY Window Functions + CTE
Practise the topic: SQL practice questions · CTE practice · Window function practice · GROUP BY exercises · Ranking function practice · Advanced SQL interview questions
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