Top Campaigns Per Region With Dense Rank | Dataford Interview Questions

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

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