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
折翼的恶魔14 分钟前
SQL 189 统计有未完成状态的试卷的未完成数和未完成率
数据库·sql
yangmf204018 分钟前
如何使用 INFINI Gateway 增量迁移 ES 数据
大数据·数据库·elasticsearch·搜索引擎·gateway
运维李哥不背锅2 小时前
Ansible 的条件语句与循环详解
数据库·ansible
梦里不知身是客112 小时前
hive的SQL语句练习2
hive·hadoop·sql
曾凡宇先生2 小时前
OpenEuler中mysql这是在执行 MySQL 密码重置操作时出现的 “找不到mysqld_safe命令” 的错误场景。
数据库·mysql
梦里不知身是客112 小时前
hive的SQL练习3
hive·hadoop·sql
方二华2 小时前
6 mysql源码中的查询逻辑
数据库·mysql
意疏3 小时前
LibreTV无广告观影实测:聚合全网资源,远程访问家庭影院新方案!
数据库
不见长安在3 小时前
mysql线上主从集群设置
数据库·mysql
tiging3 小时前
mysql 如何让事件执行
数据库·mysql