SQL查询：加入工会的结果，所有查询

Question

下面我有以下SQL查询：

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

现在我需要过滤此表的基础上的一些类型，它是在不同的表中的结果。比方说，连接会是这样：

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

我想低于此，但没有运气，我仍然得到大量的全部总和。

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 

我该如何做到这一点？

Answer 1

如果我理解正确的话，从select删除id：

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

在发言的问题是，你有一个LEFT JOIN将始终包括的加入左侧的所有行。

如果您在做A LEFT JOIN B ON ...这将总是返回A中的所有行。如果A和B之间没有匹配，则B的列值将为NULL。

你需要的是一个INNER JOIN，它只返回在A INNER JOIN B ON ...之间A和B匹配的行。你的情况，这只会返回一个如果你想通过ID分组的款项满足于B.

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相应的收益类型行：

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; 

---

如果你想总和对于所有Id's：

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;