Top Suppliers by Category | Dataford Interview Questions

Write a SQL query using window functions to identify the top three suppliers by transaction volume for each product category. Assume transaction volume means the number of transaction records. Include ties at the third rank.

Output

One row per qualifying supplier and product category, with category_name, supplier_name, transaction_volume, and supplier_rank.
Include only suppliers ranked 1 through 3 within their category, ordered by category, rank, and supplier name.

Schema

product_categories

Column	Type	Description
category_idPK	INT	Unique product category identifier
category_name	VARCHAR(100)	Product category name

suppliers

Column	Type	Description
supplier_idPK	INT	Unique supplier identifier
supplier_name	VARCHAR(150)	Supplier name

supplier_transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
category_id	INT	Referenced product category
supplier_id	INT	Referenced supplier

Your question is Top Suppliers by Category. Start with the requirements and the three tables in the Question tab.

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Problem