如何删除没有唯一行id存在的重复行?
我的座位是
col1 col2 col3 col4 col5 col6 col7
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
我想留下以下重复删除后:
john 1 1 1 1 1 1
sally 2 2 2 2 2 2
我尝试了一些查询，但我认为他们取决于有一个行id，因为我没有得到想要的结果。例如:
DELETE
FROM table
WHERE col1 IN (
SELECT id
FROM table
GROUP BY id
HAVING (COUNT(col1) > 1)
)
当前回答
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
其他回答
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)
微软有一个关于如何删除重复文件的非常简洁的指南。查看http://support.microsoft.com/kb/139444
简而言之，当你只有几行要删除时，下面是删除重复项的最简单方法:
SET rowcount 1;
DELETE FROM t1 WHERE myprimarykey=1;
Myprimarykey是行标识符。
我将rowcount设置为1，因为我只有两行复制。如果我复制了3行，那么我就会将rowcount设置为2，这样它就会删除它看到的前两行，只在表t1中留下一行。
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。
with myCTE
as
(
select productName,ROW_NUMBER() over(PARTITION BY productName order by slno) as Duplicate from productDetails
)
Delete from myCTE where Duplicate>1
