1.首先更改my.cnf的配置文件，并重启mysql

  1. [root@localhost ~]# vim /etc/my.cnf
  2. [mysqld]
  3. skip-grant-tables
  4. [root@localhost ~]# systemctl restart mysqld

2.登录MySQL,此时不需要输入密码，直接回车即可

  1. mysql -uroot -p

3.切换到mysql数据库，查询user表的结构，这里有需要的字段

在MySQL5.7版本中mysql数据库下已经没有password这个字段了，password字段改成了authentication_string字段。把这个复制下来，修改密码时会用到，当然也可以手打。
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4.修改mysql的root密码并退出mysql

  1. mysql> update user
  2.     -> set authentication_string=password('ABCabc123!')
  3.     -> where user='root' and host='localhost';
  4. Query OK, 0 rows affected, 1 warning (0.00 sec)
  5. Rows matched: 0  Changed: 0  Warnings: 1
  7. mysql> \q
  8. Bye

5.再次修改my.cnf配置文件，将第一步添加的语句注释或删除,然后重启mysql

  1. [root@localhost ~]# vim /etc/my.cnf
  2. [mysqld]
  3. #skip-grant-tables
  4. [root@localhost ~]# systemctl restart mysqld

6.用新密码登录mysql

  1. [root@localhost ~]# mysql -uroot -pABCabc123!
  2. mysql: [Warning] Using a password on the command line interface can be insecure.
  3. Welcome to the MySQL monitor.  Commands end with ; or \g.
  4. Your MySQL connection id is 2
  5. Server version: 5.7.14 MySQL Community Server (GPL)
  7. Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
  9. Oracle is a registered trademark of Oracle Corporation and/or its
  10. affiliates. Other names may be trademarks of their respective
  11. owners.
  13. Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
  15. mysql>

7.修改默认密码

  1. MySQL [(none)]> show databases;
  2. ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
  1. MySQL [(none)]> alter user user() identified by 'ABCabc123!';
  2. Query OK, 0 rows affected (0.00 sec)