Question

我得到了大约5个用户的列表，这些用户在表格中有重复的条目。这是我用来获取重复条目的查询。请建议删除一些条目的简单方法。

USE [DB]

SELECT UserName, COUNT(*) AS CountOF 
FROM UserDetails
WHERE RoleID = '2'
GROUP BY UserName
HAVING COUNT(*) > 1

Answer 1

使用方括号表示SQL Server。如果是这样，你可以这样做：

WITH todelete as (
      SELECT ud.*,
             ROW_NUMBER() OVER (PARTITION BY RoleId, username ORDER BY RoleId) as seqnum
      FROM UserDetails
      WHERE RoleID = 2
     )
DELETE FROM todelete
    WHERE seqnum > 1;

注意：如果RoleId是数字，则不要将该值与字符串进行比较。

Answer 2

需要另一个uniq列，如id或createtime 更多数据库支持

with repeatData as (
    SELECT UserName,COUNT(*) as CountOF,min(id) as keepTag FROM UserDetails
    WHERE RoleID = '2'
    GROUP BY UserName
    HAVING COUNT(*)>1),
toDelData as (
    select id from UserDetails 
    where UserName in (SELECT UserName from repeatData) 
    and id not in (SELECT keepTag from repeatData) )
delete FROM UserDetails where id in (select id from toDelData )

从sql中的表中删除几个重复的行

2 个答案: