SQL MoM Sign-Up Growth | Dataford Interview Questions

Write a SQL query to calculate the month-over-month growth rate of student sign-ups from a specific marketing channel.

Use the provided Guild marketing-channel and student-signup data. Calculate results for the Guild Paid Search channel, and return a NULL growth rate for the first month because no prior month exists.

Output

One row per month for the selected channel
Columns: month_start, signup_count, previous_month_signups, and growth_rate_percent
Include the first month with NULL prior-month and growth values
Order by month_start ascending

Schema

student_signups

Column	Type	Description
signup_idPK	INT	Unique student signup identifier
student_id	INT	Identifier of the student who signed up
channel_id	INT	Marketing channel associated with the signup
signed_up_at	TIMESTAMP	Timestamp when the student signed up

marketing_channels

Column	Type	Description
channel_idPK	INT	Unique marketing channel identifier
channel_name	VARCHAR(100)	Marketing channel name
channel_type	VARCHAR(50)	High-level channel classification

Your question is SQL MoM Sign-Up Growth. Start with the requirements and the two tables in the Question tab.

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Problem