SQL 帮助 - 从连接返回重复项答案

【问题标题】：SQL help - returning duplicates from joinSQL 帮助 - 从连接返回重复项
【发布时间】：2010-12-17 10:31:12
【问题描述】：

我的 SQL 查询连接到多个表，因此它显示了多个结果。我知道 SELECT DISTINCT，但其中一个字段 ('Account.Name') 偶尔会有所不同，因此它将这条记录视为新行。有任何想法吗？这是我的 SQL：

    SELECT DISTINCT 
                      d.ID, ISNULL(d.OnHold, 0) AS 'OnHold', d.OnHoldReason AS 'On Hold Reason', d.LegacyID AS 'Consignment#', d.IntConNo AS 'Consignment Ref', 
                      CASE WHEN JobType = 'O' THEN 'Outward' ELSE 'Collection' END AS 'Job Type', d.TripDate AS 'Delivery Date', d.DeliveryTown AS 'Delivery Town', 
                      d.DeliveryPostcode AS 'Delivery Postcode', d.VehicleReg AS 'Vehicle Reg', d.RequiredCollectionDate AS 'Req. Collection Date', 
                      d.VehicleReg AS 'Vehicle Registration', CASE WHEN d .DeliveryStatus = 2 THEN 'OK' END AS 'Delivery Status', d.ItemsignedBy AS 'POD Signed By', 
                      d.BaseRate AS 'Base Rate', d.FuelSurcharge AS 'Fuel Surcharge', d.AdditionalCharges AS 'Additional Charges', 
                      d.BaseRate + d.FuelSurcharge + d.AdditionalCharges AS 'Value', CASE WHEN InvoiceNumber IS NULL THEN CONVERT(bit, 0) ELSE CONVERT(bit, 1) 
                      END AS Tagged, CASE WHEN di.Total = di.Delivered THEN 'Recieved' ELSE 'Not Recieved' END AS 'Items', Account.Name
FROM         Deliveries AS d LEFT OUTER JOIN
                          (SELECT     Consignment, COUNT(*) AS Total, COUNT(CASE WHEN Status = 2 THEN 1 END) AS Delivered
                            FROM          Items
                            GROUP BY Consignment) AS di ON d.ID = di.Consignment INNER JOIN
                      Account ON d.Customer = Account.InvoiceAccount
WHERE     (d.InvoiceNumber IS NULL) AND (d.TripDate > 29 / 11 / 2010)
ORDER BY 'Consignment#'

【问题讨论】：

如果 Account.Name 不同，则为新记录。我不清楚您要限制什么。如果您不想看到所有出现的 Account.Name 则不要返回它或使用子选择或 sproc 来生成包含所有 Account.Name 实例的聚合字段（即连接）。

标签： c# asp.net sql

【解决方案1】：

最简单的解决方案是将 DISTINCT 替换为 GROUP BY。缺点是只返回一个帐户名。

其他解决方案可能是

创建一个返回连接帐户名称的函数
使用子选择只返回一个名称

使用分组方式

SELECT  d.ID
        , ISNULL(d.OnHold, 0) AS 'OnHold'
        , d.OnHoldReason AS 'On Hold Reason'
        , d.LegacyID AS 'Consignment#'
        , d.IntConNo AS 'Consignment Ref'
        , CASE WHEN JobType = 'O' THEN 'Outward' ELSE 'Collection' END AS 'Job Type'
        , d.TripDate AS 'Delivery Date'
        , d.DeliveryTown AS 'Delivery Town'
        , d.DeliveryPostcode AS 'Delivery Postcode'
        , d.VehicleReg AS 'Vehicle Reg'
        , d.RequiredCollectionDate AS 'Req. Collection Date'
        , d.VehicleReg AS 'Vehicle Registration'
        , CASE WHEN d .DeliveryStatus = 2 THEN 'OK' END AS 'Delivery Status', d.ItemsignedBy AS 'POD Signed By'
        , d.BaseRate AS 'Base Rate'
        , d.FuelSurcharge AS 'Fuel Surcharge'
        , d.AdditionalCharges AS 'Additional Charges'
        , d.BaseRate + d.FuelSurcharge + d.AdditionalCharges AS 'Value'
        , CASE WHEN InvoiceNumber IS NULL THEN CONVERT(bit, 0) ELSE CONVERT(bit, 1) END AS Tagged
        , CASE WHEN di.Total = di.Delivered THEN 'Recieved' ELSE 'Not Recieved' END AS 'Items'
        , MIN(Account.Name)
FROM    Deliveries AS d 
        LEFT OUTER JOIN (
          SELECT  Consignment
                  , COUNT(*) AS Total
                  , COUNT(CASE WHEN Status = 2 THEN 1 END) AS Delivered
          FROM    Items
          GROUP BY 
                  Consignment
        ) AS di ON d.ID = di.Consignment 
        INNER JOIN Account ON d.Customer = Account.InvoiceAccount
WHERE   (d.InvoiceNumber IS NULL) 
        AND (d.TripDate > 29 / 11 / 2010)
GROUP BY
        d.ID
        , ISNULL(d.OnHold, 0)
        , d.OnHoldReason
        , d.LegacyID
        , d.IntConNo
        , CASE WHEN JobType = 'O' THEN 'Outward' ELSE 'Collection' END
        , d.TripDate
        , d.DeliveryTown
        , d.DeliveryPostcode
        , d.VehicleReg
        , d.RequiredCollectionDate
        , d.VehicleReg
        , CASE WHEN d .DeliveryStatus = 2 THEN 'OK' END AS 'Delivery Status', d.ItemsignedBy
        , d.BaseRate
        , d.FuelSurcharge
        , d.AdditionalCharges
        , d.BaseRate + d.FuelSurcharge + d.AdditionalCharges
        , CASE WHEN InvoiceNumber IS NULL THEN CONVERT(bit, 0) ELSE CONVERT(bit, 1) END
        , CASE WHEN di.Total = di.Delivered THEN 'Recieved' ELSE 'Not Recieved' END
ORDER BY 
        'Consignment#'

【讨论】：

谢谢哥们，我想我会沿着子选择路线走。