先理解触发器的概念你的问题可以这么用存储过程解决:
update a
set MonthCount=(select sum(Count_Working ) from tablename where WorkDay<=a.WorkDay and WorkDay>=dateadd(day,1-datepart(day,a.WorkDay),a.WorkDay) and
ID_Station=a.ID_Station and ID_Shift=a.ID_Shift and WorkingProcedure=a.WorkingProcedure)
from tablename a
update a
set MonthCount=(select sum(Count_Working ) from tablename where WorkDay<=a.WorkDay and WorkDay>=dateadd(day,1-datepart(day,a.WorkDay),a.WorkDay) and
ID_Station=a.ID_Station and ID_Shift=a.ID_Shift and WorkingProcedure=a.WorkingProcedure)
from tablename a
set MonthCount=(select sum(Count_Working ) from tablename where WorkDay<=a.WorkDay and datadiff(mm,WorkDay,a.WorkDay)=0 and
ID_Station=a.ID_Station and ID_Shift=a.ID_Shift and WorkingProcedure=a.WorkingProcedure)
from tablename a