Question

我在下面有以下SQL查询：

select SUM(Amount) Amount 
from
    (
        select Amount from IncomeSource1
        union all
        select Amount from IncomeSource2
    ) inc

现在我需要根据不同表中的某些类型过滤此表的结果。让我们说连接将是这样的：

select Amount 
from IncomeSource1 ic1
     left join IncomeType it on it.id = ic1.id
where it.IncomeType = 1

我正在尝试以下但没有运气，我仍然得到所有金额。

select Id, SUM(Amount) Amount 
from
    (
        select Id, Amount from IncomeSource1
        union all
        select Id, Amount from IncomeSource2
    ) inc
    left join IncomeType it on it.id = inc.id and it.IncomeType = 1

我怎样才能做到这一点？

Answer 1

如果我理解正确，请从id

中删除select

select SUM(Amount) as Amount
from (select Id, Amount from IncomeSource1
      union all
      select Id, Amount from IncomeSource2
     ) inc left join
     IncomeType it
     on it.id = inc.id and it.IncomeType = 1;

Answer 2

您的陈述中的问题是您有一个LEFT JOIN，它将始终包含联接左侧的所有行。

如果您正在执行A LEFT JOIN B ON ...，则始终将返回A中的所有行。如果A和B之间不匹配，则B的列值将为NULL。

您需要的是INNER JOIN，它只会返回A INNER JOIN B ON ...中A和B之间匹配的行。在你的情况下，这只会返回A中满足B中相应收入类型的行。

如果您想要按Id分组的总和：

select Id, SUM(Amount) Amount 
from
    (
        select Id, Amount from IncomeSource1
        union all
        select Id, Amount from IncomeSource2
    ) inc
    inner join IncomeType it on it.id = inc.id and it.IncomeType = 1
group by id;

如果你想要所有Id的总和：

select SUM(Amount) Amount 
from
    (
        select Id, Amount from IncomeSource1
        union all
        select Id, Amount from IncomeSource2
    ) inc
    inner join IncomeType it on it.id = inc.id and it.IncomeType = 1;

SQL查询：加入union all查询的结果

2 个答案: