如何组合两个具有来自不同表和多个列的计数的查询

Question

我有一个查询返回两个表中的count和一些列，另一个查询返回两个表中的count和一列。 我想结合这两个查询，每个id导致单行。 我试过这个：

select 
(select a.column_1 as ID,a.column_2,COUNT(b.column_2) as Cnt1
from
    table_1 a left outer join table_2 b on a.ID=b.ID
group by 
    a.column_1 as ID,a.column_2
)
where EXISTS
(select a.column_1 as ID,COUNT(c.column_2) as Cnt2
from
    table_1 a left outer join table_3 c on a.ID=c.ID
group by
    a.column_1
) 

Answer 1

在不知道您的真实架构的情况下...基于您的示例查询，假设您的内部查询是正确的（一些小的语法错误）。你可能想做这样的事情。

select *
FROM
  (select a.column_1 as ID,a.column_2,COUNT(b.column_2) as Cnt1
    from table_1 a left outer join table_2 b on a.ID=b.ID
    group by a.column_1,a.column_2
  ) T1
INNER JOIN
  (select a.column_1 as ID,COUNT(c.column_2) as Cnt2
    from table_1 a left outer join table_3 c on a.ID=c.ID
    group by a.column_1
  ) T2 ON T1.ID = T2.ID

sqlfiddle

您可能希望根据评论将select *替换为select T1.ID,T1.column_2,Cnt1,Cnt2。