SQL 7-Day Rolling Average | Dataford Interview Questions

Your question is SQL 7-Day Rolling Average. Start with the requirements and the two tables on the right.

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Problem

Keyrus France's Data Intelligence reporting needs a daily view of conversions from active campaigns. Write a PostgreSQL query for the period from 2024-06-01 through 2024-06-10.

Requirements

Count only events with conversion_status = 'converted' belonging to active campaigns.
Return every calendar date in the period, including dates with zero conversions.
Calculate a seven-day rolling average using the current date and up to the six preceding calendar days.
Return conversion_date, daily_conversions, and rolling_7_day_average, ordered chronologically. Round the average to two decimal places.

Schema

campaigns

Column	Type	Description
campaign_idPK	INTEGER	Unique campaign identifier
campaign_name	VARCHAR(100)	Campaign display name
status	VARCHAR(20)	Campaign lifecycle status

conversion_events

Column	Type	Description
event_idPK	INTEGER	Unique conversion event identifier
campaign_id	INTEGER	Campaign associated with the event
converted_at	TIMESTAMP	Timestamp when the event occurred
conversion_status	VARCHAR(20)	Conversion processing outcome