First Order Amount per Restaurant | Dataford Interview Questions

Given an orders table (order id, order price, restaurant id) and a restaurants table, find the amount of each restaurant's first order.

Asked in the technical stage. Treat the earliest order_placed_at as the first order. If timestamps tie, use the lowest order_id as the tie-breaker.

Output

One row per restaurant, including restaurants with no orders.
Columns: restaurant_id, restaurant_name, and first_order_amount.
Sort by restaurant_id ascending. Return NULL when a restaurant has no orders or its first order amount is NULL.

Schema

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
order_price	NUMERIC(10,2)	Total price of the order
restaurant_id	INT	Restaurant associated with the order
order_placed_at	TIMESTAMP	Timestamp when the order was placed

restaurants

Column	Type	Description
restaurant_idPK	INT	Unique restaurant identifier
restaurant_name	VARCHAR(120)	Restaurant display name

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