从三个内连接表中选择不同的值答案

【问题标题】：Selecting Distinct Values from Three Inner Join Tables从三个内连接表中选择不同的值
【发布时间】：2014-04-10 06:47:04
【问题描述】：

我有三个表Order_Inventory、Order_List 和Track_Order。当我在这里执行相同的查询时，我在我的 gridView 中获得了相同订单 ID 的复制值。我想获得不同的价值观。附件是我的查询和数据库值的快照。

根据Order_Id查询订单跟踪：

SELECT
  Shopping_Order_List.Order_ID AS Order_ID, Shopping_Order_List.Product_ID,
  Shopping_Order_List.Product_Name, Shopping_Order_List.Order_Product_Quantity,
  Shopping_Order_List.Order_Discount, Shopping_Order_List.Order_Price,
  Shopping_TrackOrder.Track_ID, Shopping_TrackOrder.Status, Shopping_TrackOrder.Remarks
FROM Shopping_Order_Inventory
  INNER JOIN
    Shopping_Order_List ON Shopping_Order_Inventory.Order_ID = Shopping_Order_List.Order_ID
  INNER JOIN
    Shopping_TrackOrder ON Shopping_Order_Inventory.Order_ID = @OrderID

结果：

Track_ID  Product_ID  Product_Name  Status  Remarks         Order_ID
1         1           Nexus         False   Not Assembled   4
4         1           Nexus         True    Deliverd        4
7         1           Nexus         False   Stock Incoming  4
8         1           Nexus         False   Stock Incoming  4
1         2           Galaxy Young  False   Not Assembled   4
4         2           Galaxy Young  True    Deliverd        4
7         2           Galaxy Young  False   Stock Incoming  4
8         2           Galaxy Young  False   Stock Incoming  4
1         3           Galaxy S3     False   Not Assembled   4
4         3           Galaxy S3     True    Deliverd        4
7         3           Galaxy S3     False   Stock Incoming  4
8         3           Galaxy S3     False   Stock Incoming  4

如您所见，我有相同订单 ID 的重复值

【问题讨论】：

那么，当每个订单只需要 1 行时，您想要哪些备注，First 或 Last？
也请分享您的预期输出。
你在吗？还是自己找到解决方案？

标签： sql inner-join

【解决方案1】：

最后一个JOINed表没有链接链接

应该是

SELECT
...
FROM Shopping_Order_Inventory
  INNER JOIN
    Shopping_Order_List ON Shopping_Order_Inventory.Order_ID = Shopping_Order_List.Order_ID
  INNER JOIN
    Shopping_TrackOrder ON Shopping_Order_Inventory.Order_ID = @OrderID 
                        AND Shopping_Order_Inventory.Order_ID =Shopping_Order_Inventory.Order_ID

【讨论】：

【解决方案2】：

您有多个跟踪记录，一个订单的相同备注是否正确？

因此，要获得不同的行，您不应选择 track id 并使用 distinct 关键字来获得不同的行。

SELECT DISTINCT
  Shopping_Order_List.Order_ID AS Order_ID, Shopping_Order_List.Product_ID,
  Shopping_Order_List.Product_Name, Shopping_Order_List.Order_Product_Quantity,
  Shopping_Order_List.Order_Discount, Shopping_Order_List.Order_Price,
  Shopping_TrackOrder.Status, Shopping_TrackOrder.Remarks
FROM Shopping_Order_Inventory
  INNER JOIN
    Shopping_Order_List ON Shopping_Order_Inventory.Order_ID = Shopping_Order_List.Order_ID
  INNER JOIN
    Shopping_TrackOrder ON Shopping_Order_Inventory.Order_ID = @OrderID

【讨论】：