Question

我有两张桌子表1：

id   name   posId   Mid
1    sam    1       10
2    sid    1       10
3    jeet   1       10

表2：

id   name   posid   Mid
1    Anin   2       10
2    Nir    2       10
3    jeev   2       10

我想要一张像......这样的桌子。

posid
1
2

即;我想要有明显的＆＃34; posid＆＃34;通过加入table1和table2，其中＆＃34; Mid＆＃34; table1和table2将是相同的

Answer 1

您可以这样做：

select distinct t1.posId
from t1
where not exists (select 1 from t2 where t2.posId = t1.posId)
union all
select distinct t2.posId
from t2
where not exists (select 1 from t1 where t2.posId = t1.posId);

我认为我错误地解决了这个问题。您可以使用join：

select t1.posid, t2.posid
from t1 join
     t2
     on t1.mid = t2.mid;

要将此作为列，您需要取消忽略。这是一种方法：

select distinct (case when n.which = 1 then t1.posid else t2.posid end) as posid
from t1 join
     t2
     on t1.mid = t2.mid cross join
     (select 1 as which union all select 2 as which) n

Answer 2

我知道你希望两个表都有明显的posid。

这不高效但有效：

select distinct aa.posid
from
    (select distinct table1.posid as posid
       from table1
       join table2
         on table1.mid=table2.mid
     UNION ALL
     select distinct table2.posid as posid
       from table1
       join table2
         on table1.mid=table2.mid) aa

Answer 3

您可以将join与union

一起使用

select t1.posid
from t1 join t2 on t1.mid = t2.mid
union
select t2.posid
from t1 join t2 on t1.mid = t2.mid

如何从两个不同的表中选择不同的值

3 个答案: