用这个就可以了
begin tran
create table tb(name varchar(10),item varchar(1),value int)
insert into tb(name,item,value)
values('a','-',3)
insert into tb(name,item,value)
values('a','+',5)
insert into tb(name,item,value)
values('a','+',2)
insert into tb(name,item,value)
values('a','-',2)
--就是这一句
select name,sum(cast(item+'1' as int)*value) as value
from tb
group by name