SQL Join and Revenue Aggregation | Dataford Interview Questions

Business Context

Genpact Finance Operations needs a simple customer revenue summary for a monthly reporting extract. The source table stores customer identifiers directly with each order.

Task

Write a PostgreSQL query that returns total revenue for each named customer.

Requirements

Exclude orders that do not have a customer name.
Sum all order amounts for each customer, treating a customer with only NULL amounts as having zero revenue.
Return customers ordered from highest to lowest total revenue, with customer name as a deterministic tie-breaker.

Schema

orders

Column	Type	Description
order_idPK	INTEGER	Unique order identifier
customer_name	VARCHAR(100)	Customer name associated with the order
order_amount	NUMERIC(12,2)	Revenue amount, including possible refunds
order_date	DATE	Date the order was placed

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