MoM Growth for Active M-PESA | Dataford Interview Questions

Write a SQL query to calculate the month-over-month growth rate of active M-PESA users at Safaricom.

Use the provided users and mpesa_transactions tables. An active user has an active account and at least one successful M-PESA transaction during the month.

Output

One row per month that has a preceding month in the data.
Columns: month_start, active_users, previous_active_users, and growth_rate_pct.
Calculate growth as the percentage change from the previous month, rounded to two decimal places.
Order by month_start ascending.

Schema

users

Column	Type	Description
user_idPK	INT	Unique Safaricom user identifier
account_status	BOOLEAN	Whether the user account is currently active

mpesa_transactions

Column	Type	Description
transaction_idPK	INT	Unique transaction identifier
user_id	INT	User who initiated the transaction
transaction_timestamp	TIMESTAMP	Date and time of the transaction
service_name	VARCHAR(50)	Safaricom service used for the transaction
transaction_status	BOOLEAN	Whether the transaction completed successfully

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Problem