表a字段
id pid des
1 1 f
2 3 x
2 4 c
表b字段
pid des
1 a
2 b
3 c
4 c
我需要得到两张表的联合查询结果如下
表c
id pid des
1 1 f
1 2 null
1 3 null
1 4 null
2 1 null
2 2 null
2 3 x
2 4 c
------解决方案--------------------
select a1.*,a2.des
from (
select id,pid
from (
select distinct id from a
) as x cross join (
select distinct pid from b
) as y
) as a1 left join a a2
where a1.id=a2.id
and a1.pid=a2.pid
------解决方案--------------------
樓上倒數第二行where要改成on
最後再加上order by a1.id就OK了,呵呵
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