请问如何在保存单据之前执行触发器？

create     trigger wcmo
on [dbo].[ICStockBill]  
for insert,update                       
as
Declare @Ftrantype  int   --单据类别定义
Select  @Ftrantype=Ftrantype  from inserted   
if (@Ftrantype=28)      
begin      
update t2 set t2.fentryselfb0847=t4.fbillno  --(需要点软件的“保存“按钮才会执行更新？能否做到只要t2表有一有数据插入就更新？）   
 from inserted as t1                 
inner join icstockbillentry as t2 on t2.finterid=t1.finterid                     
inner join icmo   as t3 on t3.finterid=t2.fsourceinterid                     
inner join seorder as t4 on t4.finterid=t3.forderinterid        
return
end