Top 3 Customers Per Region | Dataford Interview Questions

OpenText wants a regional customer-spending view for account planning. Write a PostgreSQL query that identifies the three customers with the highest qualifying spend in each region during the year ending 2026-08-29.

Requirements

Join customers to regions and orders.
Include only orders from the past year, using CURRENT_DATE - INTERVAL '1 year' as the date boundary.
Aggregate order amounts by customer and region, treating customers with no qualifying orders as spending zero.
Rank customers independently within each region and return at most three per region.
Sort the final output by region name, rank, and customer ID. Use customer ID as a deterministic tie-breaker.

Schema

regions

Column	Type	Description
region_idPK	INT	Unique region identifier
region_name	VARCHAR(50)	Display name of the region

customers

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

orders

Column	Type	Description
order_idPK	INT	Unique order identifier
customer_id	INT	Customer who placed the order
order_date	DATE	Date the order was placed
order_amount	NUMERIC(12,2)	Monetary value of the order

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