SQL Query用于汇总来自不同表的字段

Question

我是一个讨厌SQL的谦虚程序员...... :)请帮我解决这个问题.

我有4个表,例如:

Table A:
Id Total
1  100
2  200
3  500

Table B
ExtId  Amount
1      10
1      20
1      13
2      12
2      43
3      43
3      22

Table C
ExtId  Amount
1      10
1      20
1      13
2      12
2      43
3      43
3      22

Table D
ExtId  Amount
1      10
1      20
1      13
2      12
2      43
3      43
3      22

我需要创建一个SELECT,它显示表B,C和D的Amount字段的Id,Total和SUM,就像这样

Id Total AmountB AmountC AmountD
1  100   43      43      43
2  200   55      55      55
3  500   65      65      65

我已尝试使用Id对三个表的内部联接并进行金额字段的总和,但结果并不严格.这是错误的查询:

SELECT     dbo.A.Id, dbo.A.Total, SUM(dbo.B.Amount) AS Expr1, SUM(dbo.C.Amount) AS  Expr2, SUM(dbo.D.Amount) AS Expr3
FROM         dbo.A INNER JOIN
                  dbo.B ON dbo.A.Id = dbo.B.ExtId INNER JOIN
                  dbo.C ON dbo.A.Id = dbo.C.ExtId INNER JOIN
                  dbo.D ON dbo.A.Id = dbo.D.ExtId
GROUP BY dbo.A.Id, dbo.A.Total

在此先感谢,它只是我讨厌SQL(或SQL讨厌我).

编辑:我有一个错字.此查询未提供正确的结果.扩展了这个例子.

Answer 1

或者您可以利用SubQueries:

select A.ID, A.Total, b.SB as AmountB, c.SC as AmountC, d.SD as AmountD
from A
  inner join (select ExtID, sum(Amount) as SB from B group by ExtID) b on A.ID = b.ExtID
  inner join (select ExtID, sum(Amount) as SC from C group by ExtID) c on c.ExtID = A.ID
  inner join (select ExtID, sum(Amount) as SD from D group by ExtID) d on d.ExtID = A.ID