select
    department,
    concat(round(sum(time) / count(sa.staff_id) * 100 ,1),'%') as ratio 
from
    (
        select
            staff_id,
            (case when (timestampdiff(second,first_clockin,last_clockin) / 3600 )> 9.5 then 1 else 0 end) 
            as time
        from
            attendent_tb
    ) as st
    left join staff_tb sa on st.staff_id = sa.staff_id
group by
    department
order by
    ratio desc