select * 
from table 
where a=isnull(@a,a) and b=isnull(@b,b) and c=isnull(@c,c) and d=isnull(@d,d)

------解决方案--------------------
SQL code
select * 
from table 
where column.a=case when isnull(a,'')!='' then a else column.a end
and column.b=case when isnull(b,'')!='' then a else column.b end
and column.c=case when isnull(c,'')!='' then a else column.c end
and column.d=case when isnull(d,'')!='' then a else column.d end

------解决方案--------------------
探讨

SQL codeselect*fromtablewhere a=isnull(@a,a)and b=isnull(@b,b)and c=isnull(@c,c)and d=isnull(@d,d)


------解决方案--------------------
探讨

SQL codeselect*fromtablewhere a=isnull(@a,a)and b=isnull(@b,b)and c=isnull(@c,c)and d=isnull(@d,d)


------解决方案--------------------
svrnfd根据需要动态构造条件语句。

------解决方案--------------------
SQL code

create proc w_wsp
@a varchar(50)=null,
@b varchar(50)=null,
@c varchar(50)=null,
@d varchar(50)=null
as
    select * from [table] where a=isnull(@a,a) and b=isnull(@b,b) and c=isnull(@c,c) and d=isnull(@d,d)
go

--调用，只有a有值时
exec w_wsp @a='aa'