您需要根据字段对重复的记录进行分组，然后保留其中一条记录并删除其余记录。 例如:

DELETE prg.Person WHERE Id IN (
SELECT dublicateRow.Id FROM
(
select MIN(Id) MinId, NationalCode
 from  prg.Person group by NationalCode  having count(NationalCode ) > 1
 ) GroupSelect
 JOIN  prg.Person dublicateRow ON dublicateRow.NationalCode = GroupSelect.NationalCode 
 WHERE dublicateRow.Id <> GroupSelect.MinId)

DELETE FROM TBL1  WHERE ID  IN
(SELECT ID FROM TBL1  a WHERE ID!=
(select MAX(ID) from TBL1  where DUPVAL=a.DUPVAL 
group by DUPVAL
having count(DUPVAL)>1))

如果你没有引用，比如外键，你可以这样做。在测试概念证明和测试数据重复时，我经常这样做。

SELECT DISTINCT [col1],[col2],[col3],[col4],[col5],[col6],[col7]

INTO [newTable]

FROM [oldTable]

进入对象资源管理器并删除旧表。

用旧表的名称重命名新表。

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

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
)

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)