sql 查询重复记录(mysql)

1、单子段(nick_name)

查询所有有重复记录的所有记录

select * from user where nick_name in (select nick_name from user group by nick_name having count(nick_name)>1);

查询出有重复记录的各个记录组中的ID最大的记录

select * from user where id in (select max(id) from user group by nick_name having count(nick_name)>1);

查询出多余的记录,不查出id最小的记录

select * from user where id in (select max(id) from user group by nick_name having count(nick_name)>1);

删除多余的重复记录,只保留id 最小的记录

delete from user where nick_name in (select nick_name from (select nick_name from user group by nick_name having count(nick_name)>1) as tmp1) and id not in (select id from (select min(id) from user group by nick_name having count(nick_name)>1) as tmp2);

2、对字段

查出所有有重复记录的记录

select * from user where (nick_name,password) in (select nick_name,password from user group by nick_name,password where having count(nick_name)>1);

查出有重复记录的各个记录组中ID最大的记录

select * from user where id in (select max(id) from user group by nick_name,password where having count(nick_name)>1);

查处各个重复记录组中多余的鸡柳数据,不查出id最小的一条

select * from user where (nick_name,password) in (select nick_name,password from user group by nick_name,password having count(nick_name)>1) and id not in (select min(id) from user group by nick_name,password having count(nick_name)>1);

删除多有的重复记录,只保留id最小的记录】

delete from user where (nick_name,password) in (select nick_name,password from (select nick_name,password from user group by nick_name,password having count(nick_name)>1) as tmp1) and id not in (select id from (select min(id) id from user group by nick_name,password having count(nick_name)>1) as tmp2);

相关推荐
果子⌂17 分钟前
Docker-构建镜像并实现LNMP架构
mysql·nginx·docker·容器·架构·php
咖丨喱44 分钟前
【Action帧简要分析】
服务器·数据库·asp.net
没饭吃!1 小时前
NHibernate案例
数据库·hibernate
泷羽Sec-静安1 小时前
OSCP官方靶场-Solstice WP
服务器·网络·数据库
IvanCodes1 小时前
Oracle 视图
大数据·数据库·sql·oracle
Trust yourself2431 小时前
使用阿里云/腾讯云安装完成mysql使用不了
mysql·阿里云·腾讯云
德育处主任Pro2 小时前
「py数据分析」04如何将 Python 爬取的数据保存为 CSV 文件
数据库·python·数据分析
许白掰2 小时前
Linux入门篇学习——Linux 编写第一个自己的命令
linux·运维·数据库·嵌入式硬件·学习
打不了嗝 ᥬ᭄2 小时前
文件系统----底层架构
linux·运维·数据库
亲爱的非洲野猪3 小时前
Oracle与MySQL详细对比
数据库·mysql·oracle