使用这个

WITH tblTemp as
(
SELECT ROW_NUMBER() Over(PARTITION BY Name,Department ORDER BY Name)
   As RowNumber,* FROM <table_name>
)
DELETE FROM tblTemp where RowNumber >1

使用CTE。这个想法是连接一个或多个列，形成一个重复的记录，然后删除你喜欢的:

;with cte as (
    select 
        min(PrimaryKey) as PrimaryKey
        UniqueColumn1,
        UniqueColumn2
    from dbo.DuplicatesTable 
    group by
        UniqueColumn1, UniqueColumn1
    having count(*) > 1
)
delete d
from dbo.DuplicatesTable d 
inner join cte on 
    d.PrimaryKey > cte.PrimaryKey and
    d.UniqueColumn1 = cte.UniqueColumn1 and 
    d.UniqueColumn2 = cte.UniqueColumn2;

alter table MyTable add sno int identity(1,1)
    delete from MyTable where sno in
    (
    select sno from (
    select *,
    RANK() OVER ( PARTITION BY RowID,Col3 ORDER BY sno DESC )rank
    From MyTable
    )T
    where rank>1
    )

    alter table MyTable 
    drop  column sno

我知道这个问题已经回答了，但我已经创建了非常有用的sp，它将为表副本创建一个动态删除语句:

    CREATE PROCEDURE sp_DeleteDuplicate @tableName varchar(100), @DebugMode int =1
AS 
BEGIN
SET NOCOUNT ON;

IF(OBJECT_ID('tempdb..#tableMatrix') is not null) DROP TABLE #tableMatrix;

SELECT ROW_NUMBER() OVER(ORDER BY name) as rn,name into #tableMatrix FROM sys.columns where [object_id] = object_id(@tableName) ORDER BY name

DECLARE @MaxRow int = (SELECT MAX(rn) from #tableMatrix)
IF(@MaxRow is null)
    RAISERROR  ('I wasn''t able to find any columns for this table!',16,1)
ELSE 
    BEGIN
DECLARE @i int =1 
DECLARE @Columns Varchar(max) ='';

WHILE (@i <= @MaxRow)
BEGIN 
    SET @Columns=@Columns+(SELECT '['+name+'],' from #tableMatrix where rn = @i)

    SET @i = @i+1;
END

---DELETE LAST comma
SET @Columns = LEFT(@Columns,LEN(@Columns)-1)

DECLARE @Sql nvarchar(max) = '
WITH cteRowsToDelte
     AS (
SELECT ROW_NUMBER() OVER (PARTITION BY '+@Columns+' ORDER BY ( SELECT 0)) as rowNumber,* FROM '+@tableName
+')

DELETE FROM cteRowsToDelte
WHERE  rowNumber > 1;
'
SET NOCOUNT OFF;
    IF(@DebugMode = 1)
       SELECT @Sql
    ELSE
       EXEC sp_executesql @Sql
    END
END

如果你创建这样的表格

IF(OBJECT_ID('MyLitleTable') is not null)
    DROP TABLE MyLitleTable 


CREATE TABLE MyLitleTable
(
    A Varchar(10),
    B money,
    C int
)
---------------------------------------------------------

    INSERT INTO MyLitleTable VALUES
    ('ABC',100,1),
    ('ABC',100,1), -- only this row should be deleted
    ('ABC',101,1),
    ('ABC',100,2),
    ('ABCD',100,1)

    -----------------------------------------------------------

     exec sp_DeleteDuplicate 'MyLitleTable',0

它将从表中删除所有重复项。如果运行它时不带第二个参数，它将返回一条SQL语句来运行。

如果您需要排除任何列，只需在调试模式下运行它，获取代码并按照您的喜好修改它。

从应用程序级别(不幸的是)。我同意防止重复的正确方法是在数据库级别上使用唯一的索引，但是在SQL Server 2005中，一个索引只能是900字节，而我的varchar(2048)字段打破了这一规定。

我不知道它的性能如何，但我认为您可以编写一个触发器来强制执行这一点，即使您不能直接使用索引。喜欢的东西:

-- given a table stories(story_id int not null primary key, story varchar(max) not null)
CREATE TRIGGER prevent_plagiarism 
ON stories 
after INSERT, UPDATE 
AS 
    DECLARE @cnt AS INT 

    SELECT @cnt = Count(*) 
    FROM   stories 
           INNER JOIN inserted 
                   ON ( stories.story = inserted.story 
                        AND stories.story_id != inserted.story_id ) 

    IF @cnt > 0 
      BEGIN 
          RAISERROR('plagiarism detected',16,1) 

          ROLLBACK TRANSACTION 
      END 

另外，varchar(2048)对我来说听起来很可疑(生活中有些东西是2048字节，但这很少见);它真的应该不是varchar(max)吗?

首先，您可以使用MIN()和Group By选择最小RowId。我们将保留这些行。

   SELECT MIN(RowId) as RowId
   FROM MyTable 
   GROUP BY Col1, Col2, Col3

删除那些不在最小RowId使用范围内的RowId

DELETE FROM MyTable WHERE RowId Not IN()

最后的查询:

DELETE FROM MyTable WHERE RowId Not IN(

    SELECT MIN(RowId) as RowId
    FROM MyTable 
    GROUP BY Col1, Col2, Col3
)

你也可以在SQL Fiddle中检查我的答案