mysql - 组合 MySQL 查询会产生错误的答案

Question

好的，我们有每个客户的大量销售数据。我可以轻松找到查询，以使用简单的查询获取每个销售代表的总销售额:

SELECT  `MerchantAddresses`.`Rep Number` AS `Rep Number`,
          SUM(`RESIDUALS_2010_12`.`Qual Cr Vol` + `RESIDUALS_2010_12`.`Qual Ch Vol`) AS `VOL_2010_12`,
          `Reps`.`First` AS `First`,
          `Reps`.`Last` AS `Last`
FROM     `MerchantAddresses`, `RESIDUALS_2010_12`, `Reps`
WHERE   `RESIDUALS_2010_12`.`MID` = `MerchantAddresses`.`MID` AND
          `Reps`.`ID` = `MerchantAddresses`.`Rep Number`
GROUP BY    `MerchantAddresses`.`Rep Number`
ORDER BY SUM(`RESIDUALS_2010_12`.`Qual Cr Vol` + `RESIDUALS_2010_12`.`Qual Ch Vol`) DESC

此代码工作得很好，返回一个按销售代表分组的单月总销售额表。目前，我们已经运行了三个单独的查询来获取 3 个月的销售数据。我想将这三个查询合并为一个。

所以，我做了以下事情:

SELECT  `MerchantAddresses`.`Rep Number` AS `Rep Number`,
          SUM(`RESIDUALS_2010_12`.`Qual Cr Vol` + `RESIDUALS_2010_12`.`Qual Ch Vol`) AS `VOL_2010_12`,
          SUM(`RESIDUALS_2010_11`.`Qual Cr Vol` + `RESIDUALS_2010_11`.`Qual Ch Vol`) AS `VOL_2010_11`,
          SUM(`RESIDUALS_2010_10`.`Qual Cr Vol` + `RESIDUALS_2010_10`.`Qual Ch Vol`) AS `VOL_2010_10`,
          `Reps`.`First` AS `First`,
          `Reps`.`Last` AS `Last`
FROM     `MerchantAddresses`, `RESIDUALS_2010_12` JOIN ON `RESIDUALS_2010_11` JOIN ON `RESIDUALS_2010_10`, `Reps`
WHERE   `RESIDUALS_2010_12`.`MID` = `MerchantAddresses`.`MID` AND
          `RESIDUALS_2010_11`.`MID` = `MerchantAddresses`.`MID` AND
          `RESIDUALS_2010_10`.`MID` = `MerchantAddresses`.`MID` AND
          `Reps`.`ID` = `MerchantAddresses`.`Rep Number`
GROUP BY  `MerchantAddresses`.`Rep Number`
ORDER BY SUM(`RESIDUALS_2010_12`.`Qual Cr Vol` + `RESIDUALS_2010_12`.`Qual Ch Vol`) DESC

我发现我实际上通过这个查询得到了不正确的值。它有效，但我为每个销售代表获得的销量值实际上太小......

有什么想法吗？谢谢!

Answer 1

我认为您不能仅仅加入这些每月表格，因为它们实际上并没有以这种方式相关。他们共享相同的商户地址，但仅此而已。

使用UNION ALL，您可以合并多个查询的结果。这样您就可以在子查询中获取所有每月记录的值，并将它们在父查询中求和。

我冒昧地在您的查询中添加了一些别名。

SELECT
  m.`Rep Number`,
  SUM(m.vol10) as VOL_2010_10,
  SUM(m.vol11) as VOL_2010_11,
  SUM(m.vol12) as VOL_2010_12,
  m.First,
  m.Last
FROM  
  (
  SELECT  
    ma.`Rep Number`,
    r10.`Qual Cr Vol` + r10.`Qual Ch Vol` AS vol10,
    null as vol11,
    null as vol12
  FROM
    MerchantAddresses ma
    INNER JOIN RESIDUALS_2010_10 as r10 on r10.MID = ma.MID
  UNION ALL
  SELECT  
    ma.`Rep Number`,
    null as vol10,
    r11.`Qual Cr Vol` + r11.`Qual Ch Vol` AS vol11,
    null as vol12
  FROM
    MerchantAddresses ma
    INNER JOIN RESIDUALS_2010_11 as r11 on r11.MID = ma.MID
  UNION ALL 
  SELECT  
    ma.`Rep Number`,
    null as vol10,
    null as vol11,
    r12.`Qual Cr Vol` + r12.`Qual Ch Vol` AS vol12
  FROM
    MerchantAddresses ma
    INNER JOIN RESIDUALS_2010_12 as r12 on r12.MID = ma.MID
  ) m
  INNER JOIN Reps r ON r.ID = m.`Rep Number`
GROUP BY
  m.`Rep Number`
ORDER BY 
  SUM(m.vol12) DESC