Window Functions for Active Mentors | Dataford Interview Questions

Write a SQL query using window functions to identify the most active mentors on MentorPass based on monthly session hours. Use completed sessions with a non-null duration, and consider all available session months.

Output

Return one row per mentor tied for the highest monthly total.
Include month, mentor_id, mentor_name, monthly_session_hours, and activity_rank.
Sort by month ascending, then mentor_id ascending.

Schema

mentors

Column	Type	Description
mentor_idPK	INT	Unique mentor identifier
mentor_name	VARCHAR(100)	Mentor display name

sessions

Column	Type	Description
session_idPK	INT	Unique mentoring session identifier
mentor_id	INT	Mentor who conducted the session
started_at	TIMESTAMP	Session start timestamp
duration_hours	NUMERIC(6,2)	Session duration in hours
status	VARCHAR(20)	Session completion status

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