SQL Total Minutes by User | Dataford Interview Questions

Write a query that accepts two date and time inputs and returns total minutes by active user, producing a result set like the sample provided with the given assumptions.

Treat the interval as half-open, including the start and excluding the end. Open sessions remain active through the requested end time. Rows with a NULL started_at are ignored, and users with no qualifying activity are excluded.

Output

One row per active user with user_id, user_name, and total_minutes.
Count each minute only once, even when that user's sessions overlap or touch.
Order by total_minutes descending, then user_id ascending.

Schema

users

Column	Type	Description
user_idPK	INT	Unique user identifier
user_name	VARCHAR(100)	Display name of the user

user_sessions

Column	Type	Description
session_idPK	INT	Unique session identifier
user_id	INT	User associated with the session
started_at	TIMESTAMP	Session start timestamp
ended_at	TIMESTAMP	Session end timestamp; NULL means the session is open
session_label	VARCHAR(50)	Source label for the session

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