试试这个
select 商品ID,定价,sum(数量) from
(select * from biao1 union all select * from biao2) group by 商品ID,定价
用UNION ALL
select 商品ID,定价,sum(数量) from
(select * from biao1 union all select * from biao2) group by 商品ID,定价
select * from 表1
union all
select * from 表2
和内连接查询一样，称为自连接查询 。求采纳
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