对与另一个表的某个列的聚合相对应的列求和

问题描述

对不起标题，但我想不出一个更好的主题。

Sorry about the title, but i couldn't think of a better subject for my issue.

我有两张桌子，多对一关系它们之间的关系以及同一表中的其他多对一关系商店。我需要对与第一张表的某个列的汇总相对应的列进行求和。

I've two tables in a many-to-one relationship between them and an other many-to-one relatioshop in the same table. I need to sum a column that corresponds a aggregate from a column of first table.

以下是说明我想要的图像：

Here is a image that illustrate what i want:

我不知道如何进行此操作。

I have no idea how to proceed with this.

推荐答案

应这样做：

SELECT  ISNULL(E.idParent,E.id) Id,
        SUM(I.Value) [Sum]
FROM EXPENSE_TABLE E
LEFT JOIN INVOICE_TABLE I
    ON I.idExpense = E.id
GROUP BY ISNULL(E.idParent,E.id)

更新的要求：

SELECT  ISNULL(E.idParent,E.id) Id,
        E2.[description],
        SUM(I.Value) [Sum]
FROM EXPENSE_TABLE E
LEFT JOIN INVOICE_TABLE I
    ON I.idExpense = E.id
INNER JOIN EXPENSE_TABLE E2
    ON ISNULL(E.idParent,E.id) = E2.id
GROUP BY ISNULL(E.idParent,E.id),
         E2.[description]

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