同一天,不考虑法定节假日下计算非加班(8-12,14-20)工作时长
(case when finish_time <= 14 then
least(finish_time-create_time,finish_time-8,12-create_time,4)
case when create_time >= 12 then
least(finish_time-create_time,finish_time -14,20-create_time,6)
case when create_time <= 8 or finish_time >= 20 then least(12-create_time,4)+least(finish_time-14,6)
else finish_time-create_time - 2)