在多个分组上具有不同功能的 SQL 查询

Question

我正在尝试将某些已售商品的收入与这些商品的保修成本进行比较。我的代码看起来像：

SELECT DISTINCT od.orderID, pa.partID, pa.price AS revenue, wa.cost AS warcost, co.description AS wardesc
FROM orders od
LEFT OUTER JOIN parts pa ON pa.orderID = od.orderID
LEFT OUTER JOIN warranties wa ON pa.partID = wa.partID
LEFT OUTER JOIN malfunctions ml ON ml.malfID = wa.malfID
LEFT OUTER JOIN components co ON ml.compID = co.compID

返回类似下面的内容。

orderID  | partID | revenue |   warcost |   wardesc<br>
1   |   1001    | 100   |   45  |   Issue #1<br>
1   |   1001 |  100  | 50  | Issue #2<br>
1   |   1002 |  200  | 55    |  Issue #3<br>
2   |   1003 |  300  | 65    |  Issue #3<br>
2   |   1003 |  300  | 70    |  Issue #4

按顺序分组，我想对战争成本求和，但只按各个部分 ID 对收入求和，所以收入不计算两次。我发现这是不可能的！

最终结果应该如下所示，期待一些帮助！

orderID |   partID |        revenue |   warcost |   wardesc<br>
1 |     1001,1002    | 300   |  150  |  Issue #1, Issue #2, Issue #3<br>
2    |  1003     |  300  |  135  |  Issue #3, Issue #4

Answer 1

试试这个：

SELECT od.orderID,
  GROUP_CONCAT(pa.partID) AS parts,
  SUM(pa.price) AS revenue,
  SUM(wa.cost) AS warcost,
  GROUP_CONCAT(co.description) AS wardesc
FROM orders od
LEFT OUTER JOIN parts pa ON pa.orderID = od.orderID
LEFT OUTER JOIN warranties wa ON pa.partID = wa.partID
LEFT OUTER JOIN malfunctions ml ON ml.malfID = wa.malfID
LEFT OUTER JOIN components co ON ml.compID = co.compID
GROUP BY od.orderID

sqlfiddle demo（这是对您所拥有的内容的简化，基于您的查询结果）

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编辑：

获取重复值可能是因为您可能在其中一个或多个连接中有多个匹配项。如果您发现无法删除重复项并且您的原始查询具有正确的结果，您可以这样做：

SELECT orderID,
  GROUP_CONCAT(partID),
  SUM(revenue),
  SUM(warcost),
  GROUP_CONCAT(wardesc)
FROM (
  SELECT DISTINCT od.orderID AS orderID,
    pa.partID AS partID,
    pa.price AS revenue,
    wa.cost AS warcost,
    co.description AS wardesc
  FROM orders od
  LEFT OUTER JOIN parts pa ON pa.orderID = od.orderID
  LEFT OUTER JOIN warranties wa ON pa.partID = wa.partID
  LEFT OUTER JOIN malfunctions ml ON ml.malfID = wa.malfID
  LEFT OUTER JOIN components co ON ml.compID = co.compID
  ) a
GROUP BY orderID