忘了mysql密码，从网上找到的解决方案记录在这里。编辑mysql的配置文件/etc/mysql/my.cnf，在[mysqld]段下加入一行“skip-grant-tables”。重启mysql服务www.linuxidc.com @ubuntu:~$ sudo service mysql restart  mysql stop/waiting  mysql star

select count(*) as U from (select count(*) as c from test.user group by b)as t where t.c >=2; select count(*) from (select count(*) from test.`user` group by b having count(*)>=2) as t ;