Top Customers by Monthly Spend | Dataford Interview Questions

Write an SQL query to find the top 3 customers by total spend each month.

Use the provided customer and order data. Include only customers with orders, and treat each order amount as spend. If customers tie, lower customer_id ranks first.

Output

One row per selected customer and month
Columns: month_start, customer_name, total_spend, and spend_rank
Include up to three customers per month, ordered by month_start, spend_rank, and customer_id

Schema

customers

Column	Type	Description
customer_idPK	INT	Unique customer identifier
customer_name	VARCHAR(120)	Customer display name

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer associated with the order
order_date	TIMESTAMP	Timestamp when the order was placed
amount	NUMERIC(12,2)	Order spend amount

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

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Problem