题解 | 统计各岗位员工平均工作时长

SELECT
    s.post,
    ROUND(
        AVG(
            TIMESTAMPDIFF (SECOND, a.first_clockin, a.last_clockin)
        ) / 3600,
        3
    ) AS work_hours
FROM
    staff_tb as s
    JOIN attendent_tb as a ON s.staff_id = a.staff_id
GROUP BY
    s.post
ORDER BY
    work_hours DESC