CentOS7下忘记MySQL数据库root密码与密码过期

• 以root用户登录linux，修改/etc/my.cnf

vim /etc/my.cnf

在[mysqld]的段中加上一句：skip-grant-tables

[mysqld] 

datadir=/var/lib/mysql 
socket=/var/lib/mysql/mysql.sock 
skip-grant-tables 

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• 退出保存，重新启动mysqld

service mysqld start
或
systemctl start mysqld

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• 登录并修改MySQL的root密码

命令如下：

/usr/bin/mysql(或直接mysql)

use mysql;

修改密码

update user set password = password('new-password') where user = 'root' ; 

or

update user set authentication_string= password('new-password') where user = 'root' ; 

• 刷新权限

flush privileges ;

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• 还原/etc/my.cnf

• 重启mysql服务

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其中在重新登录mysql时，你可能遇到如下问题：

问题一：

ERROR 2002 (HY000): Can’t connect to local MySQL server 
through socket ‘/var/lib/mysql/mysql.sock’ (2)

然后去找这个文件，发现/var/lib/mysql/路径下没有mysql.sock文件。而该文件存在于/tmp/mysql.sock !

解决方法：

① 修改my.cnf

[mysqld]

socket = /tmp/mysql.sock

② 软链

ln -s /tmp/mysql.sock  /var/lib/mysql/mysql.sock

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问题二：

ERROR 1054 (42S22): Unknown column 'password' in 'field list'

使用如下方式修改密码：

update user set authentication_string= password('new-password') where user = 'root' ; 

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问题三：

ERROR 1862 (HY000): Your password has expired. To log in you must change it using a client 
that supports expired passwords.

解决过程如下：

① 修改my.cnf，将skip-grant-tables放开，重启服务，登录mysql；

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查看用户root信息:

select * from user where user = 'root'\G;

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② 使用如下命令修改password_expired

use mysql;

update user set password_expired='N' where user='root';

flush privileges;