Rolling Average Orders by Restaurant | Dataford Interview Questions

Write an SQL query using window functions to compute a 7-day rolling average of orders per restaurant.

Use the provided restaurants and orders data for February 1 through February 7, 2025. Include calendar dates with no orders and round the rolling average to four decimal places.

Output

One row per restaurant and calendar date, ordered by restaurant_id and order_date.
Columns: restaurant_id, restaurant_name, order_date, daily_orders, and rolling_7_day_avg.
Include all restaurants and all seven dates, including zero-order days.

Schema

restaurants

Column	Type	Description
restaurant_idPK	INT	Unique restaurant identifier
restaurant_name	VARCHAR(100)	Restaurant display name

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
restaurant_id	INT	Restaurant associated with the order
order_date	DATE	Date on which the order was placed

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Problem