Explain an SQL Function | Dataford Interview Questions

I will show you an SQL function. Explain what it does and how you would validate its correctness.

Describe the intended result and validate it against representative customer and order cases, including customers without orders and orders with NULL amounts.

Output

One row per customer, ordered by customer_id.
Include the actual and expected order count, total amount, and last order date, plus a boolean is_correct validation result.

Schema

customers

Column	Type	Description
customer_idPK	INTEGER	Unique customer identifier
customer_name	VARCHAR(100)	Customer display name

orders

Column	Type	Description
order_idPK	INTEGER	Unique order identifier
customer_id	INTEGER	Customer who placed the order
amount	NUMERIC(12,2)	Order amount, which may be NULL
order_date	DATE	Date the order was placed

Your question is Explain an SQL Function. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem