Compare Region Performance Across Months | Dataford Interview Questions

You are given monthly performance data for delivery regions. Write a PostgreSQL query that compares each region’s current month performance to its previous month using a self-join. Return only months where a prior month exists, along with the month-over-month change in orders and revenue.

Schema

region_monthly_performance

Column	Type	Description
region_id	INT	Region identifier
region_name	VARCHAR(100)	Region name
month_start	DATE	First day of the month
orders_completed	INT	Completed orders in the month
gross_revenue	NUMERIC(12,2)	Gross revenue for the month

Your question is Compare Region Performance Across Months. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

Problem

Schema

region_monthly_performance

Column	Type	Description
region_id	INT	Region identifier
region_name	VARCHAR(100)	Region name
month_start	DATE	First day of the month
orders_completed	INT	Completed orders in the month
gross_revenue	NUMERIC(12,2)	Gross revenue for the month

Your question is Compare Region Performance Across Months. Start with the requirements and the one table in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.