Top Restaurants by Order Volume | Dataford Interview Questions

Your question is Top Restaurants by Order Volume. Start with the requirements and the two tables on the right.

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Problem

Swiggy's Business Analytics team wants to identify the restaurants with the highest completed order volume. Assume the report date is 2025-02-15, so the previous calendar month is January 2025.

Write a PostgreSQL query to return the top three restaurants by completed order volume during that month.

Requirements

Join restaurants to orders using restaurant_id.
Include only orders with status COMPLETED placed from 2025-01-01 through, but not including, 2025-02-01.
Return each restaurant's name and completed order count, ordered from highest to lowest. Break ties using ascending restaurant_id and return only three rows.

Schema

restaurants

Column	Type	Description
restaurant_idPK	INTEGER	Unique restaurant identifier
restaurant_name	VARCHAR(120)	Restaurant display name
city	VARCHAR(80)	Swiggy service city
is_active	BOOLEAN	Whether the restaurant is currently active

orders

Column	Type	Description
order_idPK	BIGINT	Unique order identifier
restaurant_id	INTEGER	Restaurant associated with the order
order_placed_at	TIMESTAMP	Timestamp when the order was placed
order_status	VARCHAR(20)	Order lifecycle status
order_value	NUMERIC(10,2)	Gross order value in INR