我的SQL总和返回双值

Question

以下查询

SELECT 
invoices.id,
SUM(payments.amount)
FROM adass.invoices 
INNER JOIN adass.payments ON invoices.id=payments.id_invoice 
GROUP BY invoices.id ORDER BY 1 desc LIMIT 0, 25

返回以下结果

但是，当我将另一个表连接到查询时：

SELECT 
invoices.id,
SUM(payments.amount)
FROM adass.invoices 
INNER JOIN adass.invoice_items ON invoices.id=invoice_items.id_invoice 
INNER JOIN adass.payments ON invoices.id=payments.id_invoice 
GROUP BY invoices.id ORDER BY 1 desc LIMIT 0, 25

它复制了发票ID 13919的付款金额，有效地将表中的100付款加倍

造成这种情况的原因是什么？

我添加了下面的表格内容

发票项目表

付款表

  

更新：更大的查询如下

SELECT SQL_CALC_FOUND_ROWS invoices.id,
COALESCE(SUM(invoice_items.gross),0) AS gross,
COALESCE(SUM(invoice_items.net) - SUM(invoice_items.gross),0) AS vat,
COALESCE(SUM(invoice_items.net),0) AS net,
COALESCE(SUM(payments.amount),0),
COALESCE(SUM(payments.amount) - SUM(invoice_items.net),0) AS outstanding
FROM adass.invoices 
LEFT JOIN adass.invoice_items ON invoices.id=invoice_items.id_invoice 
LEFT JOIN adass.payments ON invoices.id=payments.id_invoice 
GROUP BY invoices.id ORDER BY 1 desc LIMIT 0, 25

  

结果：   

Answer 1

很清楚发生了什么。您的INVOICE＃13919有两个发票项目，因此您获得双发票金额，因为您的查询生成了两行。如果您有三个发票项目，那么金额将增加两倍。

您需要从查询INNER JOIN adass.invoice_items ON invoices.id=invoice_items.id_invoice中删除此子句，因为您还没有使用adass.invoice_items中的列。

您的查询将是：

SELECT invoices.id,
       SUM(payments.amount)
  FROM adass.invoices 
 INNER JOIN adass.payments ON invoices.id=payments.id_invoice 
GROUP BY invoices.id ORDER BY 1 desc LIMIT 0, 25