ALTER TABLE a
ADD CHECK 
(
    (returnflag=0 and costamount=isnull(quantity,0)*isnull(costprice,0)) 
 or 
    (returnflag=1 and amount=isnull(quantity,0)*isnull(realprice,0))
)

------解决方案--------------------
探讨


引用:

SQL code
ALTER TABLE a
ADD CHECK
(costamount=
case returnflag
when 0 then isnull(quantity,0)*isnull(costprice,0)
when 1 then isnull(quantity,0)*isnull(realprice,0) end )

额，不是……