SQL查詢：加入工會的結果，所有查詢

Question

下面我有以下SQL查詢：

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

現在我需要過濾此表的基礎上的一些類型，它是在不同的表中的結果。比方說，連接會是這樣：

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

我想低於此，但沒有運氣，我仍然得到大量的全部總和。

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 

我該如何做到這一點？

Answer 1

如果我理解正確的話，從select刪除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

在發言的問題是，你有一個LEFT JOIN將始終包括的加入左側的所有行。

如果您在做A LEFT JOIN B ON ...這將總是返回A中的所有行。如果A和B之間沒有匹配，則B的列值將爲NULL。

你需要的是一個INNER JOIN，它只返回在A INNER JOIN B ON ...之間A和B匹配的行。你的情況，這隻會返回一個如果你想通過ID分組的款項滿足於B.

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相應的收益類型行：

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; 

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如果你想總和對於所有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;