DECLARE @TB TABLE(NAME VARCHAR(100));
INSERT INTO @TB VALUES ('Red'),('Red'),('Green'),('Blue'),('White'),('White')
--**Delete by Rank**
;WITH CTE AS(SELECT NAME,DENSE_RANK() OVER (PARTITION BY NAME ORDER BY NEWID()) ID FROM @TB)
DELETE FROM CTE WHERE ID>1
SELECT NAME FROM @TB;
--**Delete by Row Number** 
;WITH CTE AS(SELECT NAME,ROW_NUMBER() OVER (PARTITION BY NAME ORDER BY NAME) ID FROM @TB)
DELETE FROM CTE WHERE ID>1;
SELECT NAME FROM @TB;

哦，哇，我觉得准备这些答案太愚蠢了，他们就像专家的答案，包括所有的CTE和临时表等。

为了让它工作，我所做的只是使用MAX聚合ID列。

DELETE FROM table WHERE col1 IN (
    SELECT MAX(id) FROM table GROUP BY id HAVING ( COUNT(col1) > 1 )
)

注意:您可能需要多次运行它来删除重复，因为这一次只会删除一组重复的行。

要在SQL Server中删除表中的重复行，请执行以下步骤:

使用GROUP BY子句或ROW_NUMBER()函数查找重复的行。 使用DELETE语句删除重复的行。

设置一个示例表

DROP TABLE IF EXISTS contacts;

CREATE TABLE contacts(
    contact_id INT IDENTITY(1,1) PRIMARY KEY,
    first_name NVARCHAR(100) NOT NULL,
    last_name NVARCHAR(100) NOT NULL,
    email NVARCHAR(255) NOT NULL,
);

插入的值

INSERT INTO contacts
    (first_name,last_name,email) 
VALUES
    ('Syed','Abbas','syed.abbas@example.com'),
    ('Catherine','Abel','catherine.abel@example.com'),
    ('Kim','Abercrombie','kim.abercrombie@example.com'),
    ('Kim','Abercrombie','kim.abercrombie@example.com'),
    ('Kim','Abercrombie','kim.abercrombie@example.com'),
    ('Hazem','Abolrous','hazem.abolrous@example.com'),
    ('Hazem','Abolrous','hazem.abolrous@example.com'),
    ('Humberto','Acevedo','humberto.acevedo@example.com'),
    ('Humberto','Acevedo','humberto.acevedo@example.com'),
    ('Pilar','Ackerman','pilar.ackerman@example.com');

查询

    SELECT 
   contact_id, 
   first_name, 
   last_name, 
   email
FROM 
   contacts;

从表中删除重复的行

   WITH cte AS (
    SELECT 
        contact_id, 
        first_name, 
        last_name, 
        email, 
        ROW_NUMBER() OVER (
            PARTITION BY 
                first_name, 
                last_name, 
                email
            ORDER BY 
                first_name, 
                last_name, 
                email
        ) row_num
     FROM 
        contacts
)
DELETE FROM cte
WHERE row_num > 1;

现在要删除记录吗

我喜欢CTE和ROW_NUMBER，因为两者结合起来可以让我们看到哪些行被删除(或更新)，因此只需更改DELETE FROM CTE…SELECT * FROM CTE:

WITH CTE AS(
   SELECT [col1], [col2], [col3], [col4], [col5], [col6], [col7],
       RN = ROW_NUMBER()OVER(PARTITION BY col1 ORDER BY col1)
   FROM dbo.Table1
)
DELETE FROM CTE WHERE RN > 1

DEMO(结果不同;我想这是由于你的打字错误。

COL1    COL2    COL3    COL4    COL5    COL6    COL7
john    1        1       1       1       1       1
sally   2        2       2       2       2       2

由于使用了PARTITION by col1，这个例子通过一个列col1来确定重复项。如果你想包含多个列，只需将它们添加到PARTITION BY:

ROW_NUMBER()OVER(PARTITION BY Col1, Col2, ... ORDER BY OrderColumn)

在sql server中可以通过多种方式来实现 最简单的方法是: 将重复行表中的不同行插入到新的临时表中。然后从重复的行表中删除所有数据，然后从没有重复的临时表中插入所有数据，如下所示。

select distinct * into #tmp From table
   delete from table
   insert into table
   select * from #tmp drop table #tmp

   select * from table

使用公共表表达式(CTE)删除重复行

With CTE_Duplicates as 
(select id,name , row_number() 
over(partition by id,name order by id,name ) rownumber  from table  ) 
delete from CTE_Duplicates where rownumber!=1

DELETE from search
where id not in (
   select min(id) from search
   group by url
   having count(*)=1

   union

   SELECT min(id) FROM search
   group by url
   having count(*) > 1
)