主题：重复值问题

没看出来哪里重复了？

Select *,订单数量 - 发货数量 As 欠货数量 from (select 产品代码,产品型号规格,颜色,sum(订单数量) As 订单数量,sum(发货数量) As 发货数量 from (Select 产品代码,产品型号规格,颜色,订单数量,0 As 发货数量 from 销售订单明细  union all Select 产品代码,产品型号规格,颜色,0 As 订单数量,出仓数量 As 发货数量 from 产品明细 ) As a where 订单数量 - 发货数量 <> 0 group by 产品代码,产品型号规格,颜色) as b