Create trigger

建立MS SQL Trigger
CREATE TRIGGER emp_sal_trg ON emp
FOR INSERT,Update
AS

declare @min_sal_new NUMBER(7, 2),@min_sal_old NUMBER(7, 2)
--取得Insert update的min_sal new old值
set @min_sal_new=(SELECT ins.[min_sal] FROM inserted ins)
set @min_sal_old=(SELECT del.[min_sal] FROM deleted del)
--也可以針對特定欄位的Update作程序
IF UPDATE(min_sal)
begin
--criteria
end

建立Oracel Trigger
create or replace trigger emp_sal_trg
before insert or update of min_sal on emp
referencing old as old_value
new as new_value
for each row

--old值:old_value.min_sal
--new值:new_value.min_sal
when (條件)
begin
--criteria
end;



但DB會因為Trigger多少影響一些效能
所以要適當處理