Rank Customers by Monthly Revenue | Dataford Interview Questions

Write a SQL query using window functions to rank customers by monthly revenue within each region at Keysight Technologies.

Use the provided customer and revenue transaction data. Include customers with at least one transaction, exclude customers without a region, and treat NULL revenue as zero.

Output

One row per customer and month with columns region, revenue_month, customer_id, customer_name, monthly_revenue, and revenue_rank.
Rank customers within each region and month, with tied revenues receiving the same rank.
Order by revenue_month, region, revenue_rank, and customer_id.

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(100)	Customer business name
region	VARCHAR(50)	Customer geographic region

revenue_transactions

Column	Type	Description
transaction_idPK	INT	Unique revenue transaction identifier
customer_id	INT	Customer associated with the transaction
transaction_date	DATE	Date on which revenue was recorded
revenue	DECIMAL(12,2)	Revenue amount for the transaction

Your question is Rank Customers by Monthly Revenue. Start with the requirements and the two tables in the Question tab.

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Problem