怎样用SQL实现连接2各同构的表

[lanslotliu]

怎样用SQL实现连接2各同构的表或2各同构的查询

[啊呀]

用UNOIN联合查询

[yujohny]

select * from a
union all select * from b

select * from a where ……
union all select * from b where ……

[sdhdy]

--等值连接
select * from a,b where a.主键=b.主键
--左连接
select * from a left join b on a.主键=b.主键
--右连接
select * from a right join b on a.主键=b.主键

[lanslotliu]

是合并2各同构的查询结果

[zjcxc]

--同构纵向连接
select * from a union all select * from b

--同构横向连接
select * from a join b on a.id=b.id


--异构横向连接
select * from a join b on a.id=b.id

--异构纵向连接,注意字段顺序.
select *,null as 仅在b中存在的字段名 from a union all select *,null as 仅在a中存在的字段名 from b

[lijinqiang]

select * from table1 where...
union all
select * from table2 where ....