Question

我需要您的帮助。

我有此查询可检测双工记录：

SELECT
    name, email, COUNT(*)
FROM
    users
GROUP BY
    name, email
HAVING 
    COUNT(*) > 1

所以我需要删除结果，所以我已经尝试了：

Delete FROM
    users
GROUP BY
    name, email
HAVING 
    COUNT(*) > 1

但不起作用。能告诉我一个帮助吗？谢谢。

Answer 1

尝试以下query：

DELETE
FROM users
WHERE ID NOT IN
(SELECT MAX(ID)
FROM users
GROUP BY name, email)

Answer 2

由于您的问题中没有ID列（主键），因此假设没有ID列。因此，CTE下面将删除重复的记录。

;WITH CTE AS (
SELECT name
, email
, ROW_NUMBER() Over(Partition by name, email Order by(Select 1)) as Sno
FROM users
)
DELETE FROM CTE WHERE SNO>1

Answer 3

我假设您要仅删除重复行，而不是与重复行有关的所有行。

您可以在此处使用ROW_NUMBER。您尚未提供USERS表的整个架构，因此这里有一个示例

CREATE TABLE dbo.Users(
     Id INT IDENTITY(1,1)
    ,[Name] NVARCHAR(50)
    ,eMail NVARCHAR(50)
    ,DateCreated DATETIME
)

SELECT
     Id
    ,[Name]
    ,eMail
    ,DateCreated
    ,RN = ROW_NUMBER()OVER(PARTITION BY Name, eMail ORDER BY DateCreated ASC)  
FROM dbo.Users

您可以将此查询更改为通用表表达式，然后从中删除

;WITH cteDups
AS(
    SELECT
         Id
        ,[Name]
        ,eMail
        ,DateCreated
        ,RN = ROW_NUMBER()OVER(PARTITION BY Name, eMail ORDER BY DateCreated ASC)  
    FROM dbo.Users
)
DELETE FROM cteDups WHERE RN > 1

RN > 1仅删除重复的记录

向查询返回重复记录的查询添加DELETE | SQL服务器

3 个答案: