SQL Window Function Ranking | Dataford Interview Questions

Accenture España wants to identify the highest-value customers in each sales region. Write a SQL query to rank customers by their total revenue within each region.

Requirements

Aggregate revenue per region and customer_id.
Rank customers within each region by total revenue, highest first.
Use a window function to assign the rank.
Return only customers with at least one completed order.

Schema

regions

Column	Type	Description
region_idPK	INT	Primary key for the region
region_name	VARCHAR(100)	Region name

customers

Column	Type	Description
customer_idPK	INT	Primary key for the customer
customer_name	VARCHAR(100)	Customer name
region_id	INT	Region assigned to the customer

orders

Column	Type	Description
order_idPK	INT	Primary key for the order
customer_id	INT	Customer who placed the order
order_status	VARCHAR(20)	Order status, such as completed or cancelled
order_amount	DECIMAL(10,2)	Revenue from the order
order_date	DATE	Order date

Your question is SQL Window Function Ranking. Start with the requirements and the three tables in the Question tab.

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