Top Ad Campaigns by Conversion | Dataford Interview Questions

InMobi Product Analytics needs to compare campaign efficiency across the InMobi Exchange. Write a PostgreSQL query to identify the five campaigns with the highest conversion rate during January 2025.

Requirements

Join campaign metadata with daily performance data.
Aggregate January impressions, clicks, and conversions by campaign.
Define conversion rate as conversions divided by clicks, expressed as a percentage. Treat NULL conversions as zero and exclude campaigns with zero total clicks.
Return the top five campaigns, ordered by conversion rate descending and campaign ID ascending to break ties.

Schema

campaigns

Column	Type	Description
campaign_idPK	INT	Unique campaign identifier
campaign_name	VARCHAR(120)	Campaign name
advertiser	VARCHAR(100)	Advertiser or agency name

campaign_daily_performance

Column	Type	Description
performance_idPK	INT	Unique daily performance record
campaign_id	INT	Referenced campaign identifier
performance_date	DATE	Reporting date
impressions	INT	Number of ad impressions
clicks	INT	Number of ad clicks
conversions	INT	Number of attributed conversions

Your question is Top Ad Campaigns by Conversion. Start with the requirements and the two tables in the Question tab.

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Problem