请参见下面的删除方式。

Declare @table table
(col1 varchar(10),col2 int,col3 int, col4 int, col5 int, col6 int, col7 int)
Insert into @table values 
('john',1,1,1,1,1,1),
('john',1,1,1,1,1,1),
('sally',2,2,2,2,2,2),
('sally',2,2,2,2,2,2)

创建一个名为@table的样例表，并用给定的数据加载它。

Delete  aliasName from (
Select  *,
        ROW_NUMBER() over (Partition by col1,col2,col3,col4,col5,col6,col7 order by col1) as rowNumber
From    @table) aliasName 
Where   rowNumber > 1

Select * from @table

注意:如果您按部分给出分区中的所有列，那么按顺序没有多大意义。

我知道，这个问题是三年前问的，我的答案是蒂姆发布的另一个版本，但发布只是为了对任何人有帮助。

删除所有重复项，但删除第一个重复项(具有最小ID)

应该同样适用于其他SQL服务器，如Postgres:

DELETE FROM table
WHERE id NOT IN (
   select min(id) from table
   group by col1, col2, col3, col4, col5, col6, col7
)

另一种在不丢失信息的情况下删除重复行的方法如下:

delete from dublicated_table t1 (nolock)
join (
    select t2.dublicated_field
    , min(len(t2.field_kept)) as min_field_kept
    from dublicated_table t2 (nolock)
    group by t2.dublicated_field having COUNT(*)>1
) t3 
on t1.dublicated_field=t3.dublicated_field 
    and len(t1.field_kept)=t3.min_field_kept

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;

我更喜欢CTE从sql server表中删除重复的行

强烈推荐阅读本文::http://codaffection.com/sql-server-article/delete-duplicate-rows-in-sql-server/

保持原创性

WITH CTE AS
(
SELECT *,ROW_NUMBER() OVER (PARTITION BY col1,col2,col3 ORDER BY col1,col2,col3) AS RN
FROM MyTable
)

DELETE FROM CTE WHERE RN<>1

不保留原创

WITH CTE AS
(SELECT *,R=RANK() OVER (ORDER BY col1,col2,col3)
FROM MyTable)
 
DELETE CTE
WHERE R IN (SELECT R FROM CTE GROUP BY R HAVING COUNT(*)>1)

在mysql中有两个解决方案:

A)使用Delete JOIN语句删除重复的行

DELETE t1 FROM contacts t1
INNER JOIN contacts t2 
WHERE 
    t1.id < t2.id AND 
    t1.email = t2.email;

该查询两次引用联系人表，因此，它使用表别名t1和t2。

输出结果为:

1 查询确定，影响4行(0.10秒)

如果你想删除重复的行并保留最低的id，你可以使用下面的语句:

DELETE c1 FROM contacts c1
INNER JOIN contacts c2 
WHERE
    c1.id > c2.id AND 
    c1.email = c2.email;

B)使用中间表删除重复的行

下面是使用中间表删除重复行的步骤:

1。创建一个新表，其结构与要删除重复行的原始表相同。

2。将原始表中的不同行插入到直接表中。

3所示。将原始表中的不同行插入到直接表中。

步骤1。创建一个与原表结构相同的新表:

CREATE TABLE source_copy LIKE source;

步骤2。从原表中插入不同的行到新表中:

INSERT INTO source_copy
SELECT * FROM source
GROUP BY col; -- column that has duplicate values

步骤3。删除原始表并将直接表重命名为原始表

DROP TABLE source;
ALTER TABLE source_copy RENAME TO source;

来源:http://www.mysqltutorial.org/mysql-delete-duplicate-rows/