SQL for Lead Conversion Rates | Dataford Interview Questions

Write a SQL query to find the conversion rate of leads generated from paid search campaigns month-over-month at Tempus AI.

Treat a lead as converted when its status is converted. Include only leads associated with campaigns whose channel is paid_search.

Output

One row per month, ordered chronologically.
Columns: month_start, total_leads, converted_leads, conversion_rate, and mom_change_percentage_points.
Report conversion rates and changes as percentages rounded to two decimal places. The first month's change should be NULL.

campaigns

Column	Type	Description
campaign_idPK	INT	Unique campaign identifier
campaign_name	VARCHAR(150)	Campaign name
channel	VARCHAR(50)	Marketing acquisition channel

leads

Column	Type	Description
lead_idPK	INT	Unique lead identifier
campaign_id	INT	Campaign associated with the lead
generated_at	TIMESTAMP	Timestamp when the lead was generated
status	VARCHAR(30)	Lead lifecycle status

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