通过汇总其中的一些列来组合多行

Question

我的表中有以下数据：

+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+
| ProductName | PricePerPiece | CafeID | Quantity | TotalPrice | MemberID | OrderID |        OrderDate        | OrderTotal | ProductID |  |
+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+
| Coffee      |            10 |      1 |        1 |         10 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         1 |  |
| Mocha       |           152 |      1 |        1 |        152 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         4 |  |
| Pikachu     |            34 |      1 |        1 |         34 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         5 |  |
| Coffee      |            10 |      1 |        1 |         10 |       20 |    1009 | 2016-06-01 02:39:49.750 |         35 |         1 |  |
| Cappucino   |            25 |      1 |        1 |         25 |       20 |    1009 | 2016-06-01 02:39:49.750 |         35 |         3 |  |
+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+

我想要一个特定产品的单行，其中将其 Quantity 和 TotalPrice 添加在一起，得到以下预期输出：

+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+
| ProductName | PricePerPiece | CafeID | Quantity | TotalPrice | MemberID | OrderID |        OrderDate        | OrderTotal | ProductID |  |
+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+
| Coffee      |            10 |      1 |        2 |         20 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         1 |  |
| Mocha       |           152 |      1 |        1 |        152 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         4 |  |
| Pikachu     |            34 |      1 |        1 |         34 |       20 |    1008 | 2016-06-01 02:38:47.113 |        196 |         5 |  |
| Cappucino   |            25 |      1 |        1 |         25 |       20 |    1009 | 2016-06-01 02:39:49.750 |         35 |         3 |  |
+-------------+---------------+--------+----------+------------+----------+---------+-------------------------+------------+-----------+--+

我尝试了以下查询：

SELECT [ProductName], [PricePerPiece], [CafeID],
    SUM([Quantity]) AS [Quantity], SUM([TotalPrice]) AS [TotalPrice],
    [MemberID],[OrderID],[OrderDate],[OrderTotal],[ProductID]
    FROM [ProductOrders] GROUP BY [ProductID], [ProductName], [PricePerPiece], [CafeID], [MemberID], [OrderID], [OrderDate], [OrderTotal]

但它给出了相同的结果，只是将Coffee 行显示在一起，但没有将其Quantity 和TotalPrice 相加。请告诉我该怎么做？

Answer 1

每行中具有不同值的列，例如 OrderID、OrderDate ，查看您的预期结果集我可以假设您想要最早的记录，只需对它们的列使用 MIN 函数。

此外，只有在 select 中且未包含在任何聚合函数中的列必须在 group by 子句中，您将获得您想要的结果。

SELECT [ProductName]
     , [PricePerPiece]
     , [CafeID]
     , SUM([Quantity])   AS [Quantity]
     , SUM([TotalPrice]) AS [TotalPrice]
     , [MemberID]
     , MIN([OrderID])    AS [OrderID]
     , MIN([OrderDate])  AS [OrderDate]
     , [OrderTotal]
     , [ProductID]
FROM [ProductOrders] 
GROUP BY [ProductName]
     , [PricePerPiece]
     , [CafeID]
     , [MemberID]
     , [OrderTotal]
     , [ProductID]

Answer 2

GROUP BY 中的列过多。我建议：

• OrderID
• OrderDate
• OrderTotal

您的目标似乎不需要此信息：

SELECT [ProductName], [PricePerPiece], [CafeID],
       SUM([Quantity]) AS [Quantity], SUM([TotalPrice]) AS [TotalPrice],
       [MemberID], [ProductID]
FROM [ProductOrders]
GROUP BY [ProductID], [ProductName], [PricePerPiece], [CafeID], [MemberID];

Answer 3

OrderTotal 的每个 Coffee 行都有不同的值。您可以选择不选择OrderTotal，也可以选择SUM(OrderTotal)。

您选择但不求和（或以其他方式聚合）的任何不同值都不会组合在一起。

仔细观察：OrderDate 和 OrderID 也是如此。根据您的预期输出，您要选择MIN(OrderID), MIN(OrderDate), MAX(OrderTotal)