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
好奇的菜鸟3 小时前
如何在IntelliJ IDEA中设置数据库连接全局共享
java·数据库·intellij-idea
tan180°3 小时前
MySQL表的操作(3)
linux·数据库·c++·vscode·后端·mysql
满昕欢喜3 小时前
SQL Server从入门到项目实践(超值版)读书笔记 20
数据库·sql·sqlserver
DuelCode4 小时前
Windows VMWare Centos Docker部署Springboot 应用实现文件上传返回文件http链接
java·spring boot·mysql·nginx·docker·centos·mybatis
幽络源小助理4 小时前
SpringBoot基于Mysql的商业辅助决策系统设计与实现
java·vue.js·spring boot·后端·mysql·spring
Hello.Reader5 小时前
Redis 延迟排查与优化全攻略
数据库·redis·缓存
简佐义的博客5 小时前
破解非模式物种GO/KEGG注释难题
开发语言·数据库·后端·oracle·golang
爬山算法5 小时前
MySQL(116)如何监控负载均衡状态?
数据库·mysql·负载均衡
JAVA学习通7 小时前
Mybatis--动态SQL
sql·tomcat·mybatis
老纪的技术唠嗑局8 小时前
OceanBase PoC 经验总结(二)—— AP 业务
数据库