题解 | 统计加班员工占比

SELECT
    st.department,
    CONCAT(ROUND(COUNT(ot.staff_id)/COUNT(st.staff_id)*100 , 1),'%') ratio
FROM(
    SELECT staff_id
    FROM attendent_tb
    WHERE TIMESTAMPDIFF(MINUTE,first_clockin, last_clockin)/60 > 9.5
)ot
RIGHT JOIN staff_tb st ON ot.staff_id = st.staff_id 
GROUP BY st.department
ORDER BY ratio DESC