0x00 MySQL 用户密码位置：

• MySQL 下密码保存在 mysql 数据库 user 表中；

  
  user 表
• 表 user 中在5.7(大致是)以前有字段Password保存密码，之后，改成了 authentication_string保存密码；
  authentication_string

0x01 修改密码

• 忘记密码：

  [root@master1 ~]# mysql -uroot -p
  Enter password: 
  ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)
  

• 更改配置

  vi /etc/my.cnf
  #在mysqld模块下添加
  skip-grant-tables
  

• 重启 mysql 服务

  systemctl restart mysqld
  

• 传统修改密码语句无效

  mysql> update user set password=password('123') where user='root';
  ERROR 1054 (42S22): Unknown column 'password' in 'field list'
  

• 新的修改密码语句

  mysql> update user set authentication_string=password('123') where user='root';
  Query OK, 1 row affected, 1 warning (0.00 sec)
  Rows matched: 1  Changed: 1  Warnings: 1
  

• 更改配置重启mysql 成功登陆

  [root@master1 ~]# vi /etc/my.cnf注释 # skip-grant-tables
  [root@master1 ~]# systemctl restart mysqld
  [root@master1 ~]# mysql -uroot -p123
  mysql: [Warning] Using a password on the command line interface can be insecure.
  Welcome to the MySQL monitor.  Commands end with ; or \g.
  Your MySQL connection id is 2
  Server version: 5.7.21-log
  
  Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
  
  Oracle is a registered trademark of Oracle Corporation and/or its 
  affiliates. Other names may be trademarks of their respective owners.
  
  Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
  
  mysql>