Self-Rating on SQL and Guesstimates | Dataford Interview Questions

Rate yourself on SQL and explain how you would handle basic SQL questions and basic guesstimates.

For the hands-on portion, write a PostgreSQL query using the provided customer and order data.

Output

One row per customer, including customers without qualifying orders.
Columns: customer_id, customer_name, completed_order_count, completed_spend, and spend_band.
Include only completed orders from calendar year 2025. Sort by completed_spend descending, then customer_id ascending.

customers

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
order_date	DATE	Date the order was placed
status	VARCHAR(20)	Order lifecycle status
amount	NUMERIC(10,2)	Order amount

Your question is Self-Rating on SQL and Guesstimates. 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.

Rate yourself on SQL and explain how you would handle basic SQL questions and basic guesstimates.

For the hands-on portion, write a PostgreSQL query using the provided customer and order data.

One row per customer, including customers without qualifying orders.
Columns: customer_id, customer_name, completed_order_count, completed_spend, and spend_band.
Include only completed orders from calendar year 2025. Sort by completed_spend descending, then customer_id ascending.

customers

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
order_date	DATE	Date the order was placed
status	VARCHAR(20)	Order lifecycle status
amount	NUMERIC(10,2)	Order amount

Your question is Self-Rating on SQL and Guesstimates. 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.