[code=SQL]create table A(id   int,    code  int,     stock  int,       kc int)
insert into A values(1,           11 ,                  3  ,       4 )
insert into A values(2,           22 ,                  4  ,       19) 
insert into A values(3,           33 ,                  4  ,       5 )
insert into A values(4,           44 ,                  7  ,       2 )
insert into A values(5,           55 ,                  9  ,       7 )
create table B(id  int,     num  int,state int)
insert into B values(4,               3  ,0 )
insert into B values(2,               6 ,1)
insert into B values(1,               1 ,1)
insert into B values(2,               9 ,1)
insert into B values(5,               2 ,1)
insert into B values(5,               5 ,0)



select a.id,a.code,a.stock,a.kc,bb.num
from a
left join (select id,sum(case when state =0 then 0 else num end) as num from b group by id) bb
on a.id = bb.id 
where a.kc <> a.stock + isnull(bb.num,0)
drop table a,b

/*

id          code        stock       kc          num         
----------- ----------- ----------- ----------- ----------- 
3           33          4           5           NULL
4           44          7           2           0
5           55          9           7           2

（所影响的行数为 3 行）
*/