Top 3 Categories by Merchant | Dataford Interview Questions

Write a query to find the top three PayPal transaction categories by volume for a given merchant over the last quarter.

Use merchant 101 and the quarter from 2025-04-01 through 2025-06-30. Transactions with a NULL category or NULL timestamp are ignored.

Output

One row per included category, with category_name and transaction_count.
Return at most three categories, ordered by transaction count descending, then category name ascending to break ties.

merchants

Column	Type	Description
merchant_idPK	INT	Unique PayPal merchant identifier
merchant_name	VARCHAR(100)	Merchant display name
merchant_status	VARCHAR(20)	Merchant account status

transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
merchant_id	INT	Merchant associated with the transaction
category_id	INT	Transaction category identifier
occurred_at	TIMESTAMPTZ	Timestamp when the transaction occurred
transaction_status	VARCHAR(20)	Transaction processing status

transaction_categories

Column	Type	Description
category_idPK	INT	Unique transaction category identifier
category_name	VARCHAR(60)	Transaction category name

Whenever you're ready, walk me through your approach or go straight to the code. The requirements and the three tables are in the Question tab.