SQL Growth Rate for Sign-ups | Dataford Interview Questions

Write a SQL query to calculate the month-over-month growth rate of sign-ups for a specific Zendesk product feature.

Use the signup_events table and calculate results for the Advanced AI feature across all available months. Return NULL when a previous month or valid comparison baseline does not exist.

Output

One row per month with month_start, signup_count, previous_signup_count, and growth_rate_pct
Include the feature's available months, ordered chronologically
Round growth percentages to two decimal places

Schema

signup_events

Column	Type	Description
signup_idPK	INT	Unique sign-up event identifier
user_id	INT	Identifier of the user who signed up
feature_name	VARCHAR(100)	Zendesk product feature associated with the sign-up
signed_up_at	TIMESTAMP	Timestamp when the sign-up occurred

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