select 
  a.corp_id,
  a.corp_name,
  b.salemoney,
  c.saleoutmoney,
  b.salemoney-c.saleoutmoney
from x_kcorp a
join (select sale_corp,sum(sale_money) as salemoney from x_sale group by sale_corp) b
  on a.corp_id=b.sale_corp
join (select saleout_corp,sum(saleout_money) as saleoutmoney from x_saleout group by saleout_corp) c
  on a.a.corp_id=c.saleout_corp

------解决方案--------------------

SQL code
use CSDN
go

--#1.直接减就可以
select 
    a.corp_id,
    a.corp_name,
    (select sum(b.sale_money) from x_sale where sale_corp=a.corp_id) as salemoney,
    (select sum(b.saleout_money) from x_saleout where saleout_corp=a.corp_id) as saleoutmoney,
    diff = (select sum(b.sale_money) from x_sale where sale_corp=a.corp_id) - (select sum(b.saleout_money) from x_saleout where saleout_corp=a.corp_id)
from x_kcorp a

--#2.或者用子查询
select 
    *,
    diff = salemoney - saleoutmoney
from
(
    select 
        a.corp_id,
        a.corp_name,
        (select sum(b.sale_money) from x_sale where sale_corp=a.corp_id) as salemoney,
        (select sum(b.saleout_money) from x_saleout where saleout_corp=a.corp_id) as saleoutmoney
    from x_kcorp a
) T