一个复杂的查询

[alfdu]

有两个表A,B
a表
---------------------------
a1 a2 a3
---------------------------
1 a 11
2 b 22
3 c 33
1 a 44
2 b 22
b表
---------------------------
a1 a2
---------------------------
1 a
5 e
4 d
2 b
我想通过这两个表查询得到如下的结果
---------------------------
a1 a2
---------------------------
1 a
2 b
3 c
4 d
5 e
如何来写sql语句

[stormhu]

A表和B表的关系?主、外键，知道关系才可查询。

[BrightEye]

先选出A中不重复的记录C.然后在所得到的记录集C中选择出两个表中不同的记录D,C与D联合就是结果.

[evonne_feng]

select distinct a1,a2 from a order by a1 asc
union
select a1,a2 from b

[yonghengdizhen]

(select a1,a2 from table1)union(select a1,a2 from table2) order by a1

[stormhu]

select C.a1,C.a2
from (select distinct a1,a2 from A)
union(select a1,a2 from B ) as C
order by C.a1

[sanzfm]

select distinct a1,a2 from(select a.a1 as a1,a.a2 as a2 from a union b)

[stormhu]

sorry:

应该是
select C.a1,C.a2
from ( (select distinct a1,a2 from A)
union(select a1,a2 from B ) ) as C
order by C.a1

[yonghengdizhen]

一个union直接搞定的东东..(不是union all哦)

哎!!!