with myCTE
as

(
select productName,ROW_NUMBER() over(PARTITION BY productName order by slno) as Duplicate from productDetails
)
Delete from myCTE where Duplicate>1

DELETE p1 FROM Person p1,
    Person p2
WHERE
    p1.Email = p2.Email AND p1.Id > p2.Id

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/

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

试着使用:

SELECT linkorder
    ,Row_Number() OVER (
        PARTITION BY linkorder ORDER BY linkorder DESC
        ) AS RowNum
FROM u_links

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)