根据3个Cols复制不同的记录

Question

我在名为Temp的表中有大量数据。这些数据包含重复数据。 不是整行，而是3列中的相同数据。他们是HouseNo，DateofYear，TimeOfDay。

我想只将“Temp”中的不同行复制到另一个表“ThermData”中。

基本上我想做的是将所有不同的行从Temp复制到ThermData，其中distinct（HouseNo，DateofYear，TimeOfDay）。这样的事情。

我知道我们做不到。替代我如何做到这一点。

帮助我。我已经尝试了很多东西，但还没有解决它。

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示例数据。重复的值就像.... 我想根据HouseNo，DateofYear，TimeOfDay

的值删除重复的行

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HouseNo DateofYear TimeOfDay Count
102 10/1/2009    0:00:02 AM 2
102 10/1/2009    1:00:02 AM 2
102 10/1/2009    10:00:02 AM    2

Answer 1

这是一个基于Orders表的Northwind示例。

根据（EmployeeID，ShipCity，ShipCountry）列有重复项。

如果您只执行这两行之间的代码：

/* Run everything below this line to show crux of the fix */
/* Run everything above this line to show crux of the fix */

你会看到它是如何运作的。基本上是：

（1）您在感兴趣的3列上运行GROUP BY。的（derived1Duplicates）

（2）然后使用这3列连接回表。 （on ords.EmployeeID = derived1Duplicates.EmployeeID and ords.ShipCity = derived1Duplicates.ShipCity and ords.ShipCountry = derived1Duplicates.ShipCountry）

（3）然后对于每个组，用基数（1,2,3,4等）标记它们（使用ROW_NUMBER（））

（4）然后在每个组中保留基数为“1”的行。 （其中derived2DuplicatedEliminated.RowIDByGroupBy = 1）

    Use Northwind
    GO


declare @DestinationVariableTable table ( 
    NotNeededButForFunRowIDByGroupBy int not null ,
    NotNeededButForFunDuplicateCount int not null ,
    [OrderID] [int] NOT NULL,
    [CustomerID] [nchar](5) NULL,
    [EmployeeID] [int] NULL,
    [OrderDate] [datetime] NULL,
    [RequiredDate] [datetime] NULL,
    [ShippedDate] [datetime] NULL,
    [ShipVia] [int] NULL,
    [Freight] [money] NULL,
    [ShipName] [nvarchar](40) NULL,
    [ShipAddress] [nvarchar](60) NULL,
    [ShipCity] [nvarchar](15) NULL,
    [ShipRegion] [nvarchar](15) NULL,
    [ShipPostalCode] [nvarchar](10) NULL,
    [ShipCountry] [nvarchar](15) NULL
)


INSERT INTO @DestinationVariableTable (NotNeededButForFunRowIDByGroupBy , NotNeededButForFunDuplicateCount , OrderID,CustomerID,EmployeeID,OrderDate,RequiredDate,ShippedDate,ShipVia,Freight,ShipName,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry )

Select RowIDByGroupBy , MyDuplicateCount , OrderID,CustomerID,EmployeeID,OrderDate,RequiredDate,ShippedDate,ShipVia,Freight,ShipName,ShipAddress,ShipCity,ShipRegion,ShipPostalCode,ShipCountry
From
(
/* Run everything below this line to show crux of the fix */
Select
 RowIDByGroupBy = ROW_NUMBER() OVER(PARTITION BY ords.EmployeeID , ords.ShipCity , ords.ShipCountry ORDER BY ords.OrderID )
 , derived1Duplicates.MyDuplicateCount
, ords.* 
from
  [dbo].[Orders] ords
 join
 (
select EmployeeID , ShipCity , ShipCountry , COUNT(*) as MyDuplicateCount from [dbo].[Orders] GROUP BY EmployeeID , ShipCity , ShipCountry /*HAVING COUNT(*) > 1*/
) as derived1Duplicates
on  ords.EmployeeID = derived1Duplicates.EmployeeID and  ords.ShipCity = derived1Duplicates.ShipCity and  ords.ShipCountry = derived1Duplicates.ShipCountry 
/* Run everything above this line to show crux of the fix */
)
as derived2DuplicatedEliminated
where derived2DuplicatedEliminated.RowIDByGroupBy = 1

select * from @DestinationVariableTable

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