题解 | 统计各岗位员工平均工作时长

select post, round(avg(diff),3) as work_hours
from
(
select TIMESTAMPDIFF(MINUTE,first_clockin,last_clockin)/60 as diff,staff_id
from attendent_tb where first_clockin is not null and last_clockin is not null
)t1 inner join staff_tb t2 on t1.staff_id = t2.staff_id
group by post
order by 2 desc

TIMESTAMPDIFF(HOUR,first_clockin,last_clockin) 好像只能返回整数？