如何彻底删除重复的行

Question

说我有重复行我表以及我的数据库设计是第三类： -

Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (1,'Cinthol','cosmetic soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (1,'Cinthol','cosmetic soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (1,'Cinthol','cosmetic soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (1,'Lux','cosmetic soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (1,'Crowning Glory','cosmetic soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (2,'Cinthol','nice soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (3,'Lux','nice soap','soap'); 
Insert Into tblProduct (ProductId,ProductName,Description,Category) Values (3,'Lux','nice soap','soap'); 

我只想要1每一行的情况下应该出现在我的表。因此应删除完全相同的2nd, 3rd and last row。我可以为此编写什么查询？可以在不创建临时表的情况下完成吗？只是在一个单一的查询？

感谢提前:)

Answer 1

试试这个 - 它会从表中删除所有重复：

;WITH duplicates AS 
(
    SELECT 
     ProductID, ProductName, Description, Category, 
     ROW_NUMBER() OVER (PARTITION BY ProductID, ProductName 
          ORDER BY ProductID) 'RowNum' 
    FROM dbo.tblProduct 
) 
DELETE FROM duplicates 
WHERE RowNum > 1 
GO 

SELECT * FROM dbo.tblProduct 
GO 

你的副本现在应该走了：输出为：

ProductID ProductName DESCRIPTION  Category 
    1   Cinthol   cosmetic soap  soap 
    1   Lux    cosmetic soap  soap 
    1   Crowning Glory cosmetic soap  soap 
    2   Cinthol   nice soap   soap 
    3   Lux    nice soap   soap 

Answer 2

首先使用SELECT... INTO：

SELECT DISTINCT ProductID, ProductName, Description, Category 
    INTO tblProductClean 
    FROM tblProduct 

的下降的第一个表。

Answer 3

DELETE tblProduct 
FROM tblProduct 
LEFT OUTER JOIN (
    SELECT MIN(ProductId) as ProductId, ProductName, Description, Category 
    FROM tblProduct 
    GROUP BY ProductName, Description, Category 
) as KeepRows ON 
    tblProduct.ProductId= KeepRows.ProductId 
WHERE 
    KeepRows.ProductId IS NULL 

被盗从How can I remove duplicate rows?

UPDATE：

这如果ProductID等于主键（它不是）才有效。你最好使用@marc_s'方法，但是我会留下这个以防万一有人使用PK会遇到这篇文章。

Answer 4

我不得不在几个星期前做这个......你正在使用什么版本的SQL Server？在SQL Server 2005和了，你可以使用ROW_NUMBER为您选择的一部分，并且只能选择其中ROW_NUMBER为1。我忘了确切的语法，但它是有据可查......沿着线的东西：

Select t0.ProductID, 
     t0.ProductName, 
     t0.Description, 
     t0.Category 
Into tblCleanData 
From (
    Select ProductID, 
      ProductName, 
      Description, 
      Category, 
      Row_Number() Over (
       Partition By ProductID, 
          ProductName, 
          Description, 
          Category 
       Order By  ProductID, 
          ProductName, 
          Description, 
          Category 
      ) As RowNumber 
    From MyTable 
) As t0 
Where t0.RowNumber = 1 

退房http://msdn.microsoft.com/en-us/library/ms186734.aspx，这应该让你朝着正确的方向前进。