Max Discount Per Category | Dataford Interview Questions

Write a query to identify products with the maximum discount per category, using the PRODUCT and PURCHASE tables.

Consider only products that appear in product at least once in purchase. Products with a NULL discount are ignored. If multiple products share the maximum discount in a category, return all of them.

Output

Return one row per qualifying product with product_id, product_name, category, and discount_percentage.
Include only products with the maximum non-NULL discount in their category.
Order by category, then product_id ascending.

Schema

product

Column	Type	Description
product_idPK	INTEGER	Unique product identifier
product_name	VARCHAR(100)	Product name
category	VARCHAR(50)	Product category
discount_percentage	NUMERIC(5,2)	Discount percentage offered on the product

purchase

Column	Type	Description
purchase_idPK	INTEGER	Unique purchase identifier
product_id	INTEGER	Purchased product identifier
purchase_date	DATE	Date of purchase
quantity	INTEGER	Number of units purchased

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Problem