Question

sql 多条件求和

3个表
批发信息
返修信息
退货信息
select isnull(sum(cast(单件总价 as float)),0) 总价 from 批发信息 where 发货日期='5.7'and 客户名='xx'
假如查询结果为1

select isnull(sum(cast(返修收费 as float)),0) 返修收费总计 from 返修信息 where 客户名='xx'and 发货日期 ='5.7'
查询结果为2

select isnull(sum(-cast(总价 as float)),0)退货金额总计 from 退货信息 where 客户名='xx'and 退货日期='5.7'
查询结果为3

怎么实现把结果1+2+3（麻烦就在要同一客户，还有就是有个日期）

请各位大虾帮帮忙··

Answer 1

select sum(总价) as 总和
from
(
select isnull(sum(cast(单件总价 as float)),0) 总价 from 批发信息 where 发货日期='5.7'and 客户名='xx'
union all
select isnull(sum(cast(返修收费 as float)),0) 返修收费总计 from 返修信息 where 客户名='xx'and 发货日期 ='5.7'
union all
select isnull(sum(-cast(总价 as float)),0)退货金额总计 from 退货信息 where 客户名='xx'and 退货日期='5.7'
)

Answer 2

select (isnull(sum(cast(a.单件总价 as float)),0)+isnull(sum(cast(b.返修收费 as float)),0)+isnull(sum(-cast(c.总价 as float)),0)) as 结果 from 批发信息 a,返修信息 b,退货信息 c where a.客户名='xx' and b.客户名='xx' and c.客户名='xx' and a.发货日期='5.7' and b.发货日期 ='5.7' and c.退货日期='5.7';