mssql trigger
CREATE   TRIGGER   upd_return_trigger

ON   [dbo].[STOCK_MALL_RETURNS]  

FOR   UPDATE  

AS

begin

update   stock_mall

set  

stock_mall.now_55=stock_mall.now_55   -(select   sum(sm.return_55)   from   inserted   as   sm   where   stock_mall.code=sm.code   and   stock_mall.color=sm.color   and   stock_mall.c_id=   sm.c_id   and   sm.status   =   '1 '   ),
stock_mall.now_66=stock_mall.now_66   -(select   sum(sm.return_66)   from   inserted   as   sm   where   stock_mall.code=sm.code   and   stock_mall.color=sm.color   and   stock_mall.c_id=   sm.c_id   and   sm.status   =   '1 '   ),
stock_mall.now_77=stock_mall.now_77   -(select   sum(sm.return_77)   from   inserted   as   sm   where   stock_mall.code=sm.code   and   stock_mall.color=sm.color   and   stock_mall.c_id=   sm.c_id   and   sm.status   =   '1 '   ),
stock_mall.now_88=stock_mall.now_88   -(select   sum(sm.return_88)   from   inserted   as   sm   where   stock_mall.code=sm.code   and   stock_mall.color=sm.color   and   stock_mall.c_id=   sm.c_id   and   sm.status   =   '1 '   )

end


现在的问题是更新sm.status= '1 '，sum（sm.return_55,66,77,88）是空值，而stock_mall.now_55,66,77,88却不能为空，请问各位这个trigger到底问题出现在哪里啊，小弟搞了两天也没解决好

我用以下方法更新：

CREATE   TRIGGER   upd_return_trigger

ON   [dbo].[STOCK_MALL_RETURNS]  

FOR   UPDATE  

AS

begin

update   stock_mall

set  

stock_mall.now_55=stock_mall.now_55   -sm.return_55,
stock_mall.now_66=stock_mall.now_66   -sm.return_66,
stock_mall.now_77=stock_mall.now_77   -sm.return_77,
stock_mall.now_88=stock_mall.now_88   -sm.return_88


from   inserted   as   sm

where   stock_mall.code=sm.code   and   stock_mall.color=sm.color   and   stock_mall.c_id=   sm.c_id   and   sm.status   =   '1 '


end


也有点问题，可以更新数据，但两边更新的值不相等

这是怎么回事




------解决方案--------------------
CREATE TRIGGER upd_return_trigger
ON [dbo].[STOCK_MALL_RETURNS]
FOR UPDATE
AS
begin
update stock_mall
set
stock_mall.now_55=stock_mall.now_55 -isnull((select sum(sm.return_55) from inserted as sm where stock_mall.code=sm.code and stock_mall.color=sm.color and stock_mall.c_id= sm.c_id and sm.status = '1 ' ),0),
stock_mall.now_66=stock_mall.now_66 -isnull((select sum(sm.return_66) from inserted as sm where stock_mall.code=sm.code and stock_mall.color=sm.color and stock_mall.c_id= sm.c_id and sm.status = '1 ' ),0),
stock_mall.now_77=stock_mall.now_77 -isnull((select sum(sm.return_77) from inserted as sm where stock_mall.code=sm.code and stock_mall.color=sm.color and stock_mall.c_id= sm.c_id and sm.status = '1 ' ),0),
stock_mall.now_88=stock_mall.now_88 -isnull((select sum(sm.return_88) from inserted as sm where stock_mall.code=sm.code and stock_mall.color=sm.color and stock_mall.c_id= sm.c_id and sm.status = '1 ' ),0)
end
------解决方案--------------------
--try

CREATE TRIGGER