请问这样子的表，怎样进行联合查询啊？

就是最后出来结果，把下面的表的数量加到上面的表里面去。下面表的产品id就是上面表的ID。

实行分组后能够获得这个结果，但是应该怎样把他的数量加到库存表里面去呢？

select id,sum([数量])
(select id,[数量] from [库存表]
union
select id,[数量] from [出库单详情])
group by id

select id,sum([数量])
(select id,[数量] from [库存表]
union
select id,[数量] from [出库单详情]) a
group by id

select id,sum([数量]) from
(select id,[数量] from [库存表]
union
select id,[数量] from [出库单详情]) a
group by id

select id,sum([数量]) from
(select id,[数量] from [库存表]
union
select 产品ID,[数量] from [出库单详情]) a
group by id
谢谢楼上的帮助。