求一条SQL语句(两个表的内容比较)

[vlonly]

表a
ID1 TYPE PRICE
A001 0 25
A002 1 70
A003 1 100
A004 0 800

表b
ID2 PRICE1 PRICE2
A002 50 156
A001 25 50
A003 100 200
A004 236 846

把根据ID把两个表不一样的PRICE显示出来 其中表b sum(PRICE2-PRICE1)
我写的语句:
select id1,price from a where not exists(select * from b where a.id1=b.id2 and a.price=
(select id2, sum(price2-price1)as price3 from b group by id2))

提示：当没有用 EXISTS 引入子查询时，在选择列表中只能指定一个表达式。请问怎么解决！

[fakedown]

create table a (id1 char(4),type int,price int)
insert a select 'A001',0,25
insert a select 'A002',1,70
insert a select 'A003',1,100
insert a select 'A004',0,800

create table b (id2 char(4),PRICE1 int,PRICE2 int)
insert b select 'A002',50,156
insert b select 'A001',25,50
insert b select 'A003',100,200
insert b select 'A004',236,846

select a.id1,max(type),max(price),sum(PRICE2-PRICE1)
from a join b on a.id1=b.id2
group by a.id1
having max(price)<>sum(PRICE2-PRICE1)