Top Campaigns Per Region With Dense Rank | Dataford Interview Questions

Your question is Top Campaigns Per Region With Dense Rank. Start with the requirements and the two tables on the right.

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

Problem

EXL Service Philippines marketing analysts need to compare campaign performance across regional markets. Write a PostgreSQL query that identifies the highest-performing campaigns in each region based on total conversions.

Requirements

Aggregate conversion totals for each campaign, including campaigns without performance records.
Use DENSE_RANK() to rank campaigns separately within each region.
Return every campaign with a rank of 3 or better. Because dense ranking preserves ties, a region may return more than three campaigns.
Sort the output by region, performance rank, and campaign name.

Schema

campaigns

Column	Type	Description
campaign_idPK	INT	Unique campaign identifier
campaign_name	VARCHAR(100)	Name of the marketing campaign
region	VARCHAR(50)	Philippine region targeted by the campaign

campaign_performance

Column	Type	Description
performance_idPK	INT	Unique performance record identifier
campaign_id	INT	References campaigns.campaign_id
reporting_date	DATE	Date covered by the performance record
conversions	INT	Number of attributed conversions