Top CTR Campaigns by Day | Dataford Interview Questions

PulsePoint needs a daily view of its strongest advertising campaigns. Assume the query runs on 2026-08-29, so the past week is 2026-08-23 through 2026-08-29. Write a PostgreSQL query that returns the top three campaigns by click-through rate for each day with valid campaign metrics.

Requirements

Join daily campaign metrics to campaigns to include the campaign name.
Filter metrics to the inclusive seven-day period ending on CURRENT_DATE, and exclude rows with zero impressions or NULL clicks.
Calculate CTR as clicks divided by impressions, expressed as a percentage rounded to two decimal places.
Rank campaigns independently for each day, returning at most three per day. Break CTR ties with the lower campaign_id.

Schema

campaigns

Column	Type	Description
campaign_idPK	INT	Unique campaign identifier
campaign_name	VARCHAR(100)	PulsePoint campaign name

daily_campaign_metrics

Column	Type	Description
metric_idPK	INT	Unique daily metric row identifier
campaign_id	INT	Campaign associated with the metrics
metric_date	DATE	Date on which metrics were recorded
clicks	INT	Number of ad clicks
impressions	INT	Number of ad impressions

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