Top Customers SQL Query | Dataford Interview Questions

Your question is Top Customers SQL Query. Start with the requirements and the two tables on the right.

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Problem

Google Cloud Marketplace needs a customer leaderboard based on completed orders. Write a PostgreSQL query that identifies the five customers with the greatest completed-order spending.

Requirements

Return each customer's customer_id, customer_name, and total completed-order value as total_spent.
Include customers without completed orders, treating their total as zero.
Exclude cancelled and refunded orders from the spending calculation.
Sort by total spending descending, use customer_id ascending as a deterministic tie-breaker, and return only five rows.

Schema

customers

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

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
order_status	VARCHAR(20)	Current order status
order_total	NUMERIC(10,2)	Order value in USD