使用2个内部连接时如何显示准确的总和？

Question

我想要得到结果：

  

引用= 12345
  总资产= 14
  总订单数= 22

当我单独运行查询时，我得到了正确的结果，但是当我将两个查询放在一起时，我的结果是关闭的（这是因为表b和c不代表彼此）

我的表摘要如下：

Select a.Quote, SUM(b.Quantity) As 'Total Assets'
FROM a 
INNER JOIN b ON b.aId = a.Id
GROUP By a.Quote

  

结果：1​​2345：14

Select a.Quote, SUM(c.Quantity) As 'Total Ordered'
FROM a
INNER JOIN c on c.aId = a.Id
GROUP By a.Quote

  

结果：1​​2345：22

然而，当我把它们放在一起时：

Select a.Quote, SUM(b.Quantity)As 'Total Assets',SUM(c.Quantity) As 'Total Ordered'
FROM a
INNER JOIN b on b.Aid = a.Id
INNER JOIN c on c.Aid = a.Id
GROUP BY a.Quote

  

结果12345：56：308

我和小组一起玩了但是从来没能得到正确的结果。有什么想法吗？

到目前为止，我提出的解决方案是

With abc AS
(
 Select a.Quote, SUM(b.Quantity) As 'Total Assets'
    FROM a 
    INNER JOIN b ON b.aId = a.Id
    GROUP By a.Quote
)
SELECT abc.* , SUM(c.Quantity) As ' Total Ordered'
FROM abc
INNER JOIN c ON c.aid = a.Id
GROUP BY (all in abc)

这似乎不是获得结果的最佳方式..

Answer 1

也许使用Left JOIN。 INNER JOIN将重复b和c行。另外，请尝试查看以下结果：

Select a.Quote, b.Quantity As 'Total Assets', c.Quantity As 'Total Ordered'
FROM a
INNER JOIN b on b.Aid = b.Id
INNER JOIN c on c.Aid = c.Id
GROUP BY a.Quote

并检查它是否是正确的计算结果。然后将其与：

进行比较

Select a.Quote, b.Quantity As 'Total Assets', c.Quantity As 'Total Ordered'
FROM a
LEFT JOIN b on b.Aid = b.Id
LEFT JOIN c on c.Aid = c.Id
GROUP BY a.Quote