SQL for Feature-Engaged MAU | Dataford Interview Questions

Write a SQL query to find the monthly active users (MAU) who interacted with at least three different product features in the last 30 days.

Assume the reporting window ends at 2025-04-01 00:00:00, and include interactions from the preceding 30 days. Return only registered users and count distinct non-null features per user and calendar month.

Output

One row per qualifying user and activity month.
Columns: user_id, activity_month, and distinct_features.
Include users with at least three distinct features, ordered by activity_month ascending and user_id ascending.

Schema

users

Column	Type	Description
user_idPK	INT	Unique Meta user identifier
user_name	VARCHAR(100)	Display name of the user
email	VARCHAR(255)	User email address

feature_interactions

Column	Type	Description
interaction_idPK	INT	Unique interaction identifier
user_id	INT	User who performed the interaction
feature_name	VARCHAR(100)	Meta product feature used by the user
interacted_at	TIMESTAMP	Timestamp when the interaction occurred

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Problem