系统环境：centos7
数据库版本：mysql Ver 14.14 Distrib 5.7.29, for linux-glibc2.12 (x86_64) using EditLine wrapper
一：首先要关闭数据库，以什么方式启动的数据库就要以什么方式结束数据库
1 [root@db01 ~]#systemctl stop mysql 2 [root@db01 ~]#ss -ntl 3 State Recv-Q Send-Q Local Address:Port Peer Address:Port 4 LISTEN 0 128 *:22 *:* 5 LISTEN 0 128 [::]:22 [::]:*
二：在命令行界面执行，如下命令，执行完成后，数据库root账户的密码就清空了
[root@db01 ~]#mysqld_safe --skip-grant-tables --skip-networking & [1] 15143 [root@db01 ~]#2020-12-14T12:13:17.814024Z mysqld_safe Logging to ‘/data/mysql/data/db01.err‘. 2020-12-14T12:13:17.843723Z mysqld_safe Starting mysqld daemon with databases from /data/mysql/data
三： 登录数据库，这个时候数据库没有密码的，如下
[root@db01 ~]#mysql Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 2 Server version: 5.7.29 MySQL Community Server (GPL) Copyright (c) 2000, 2020, 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>
四：修改数据库的密码，如下
mysql> alter user root@localhost identified by ‘123456‘; ERROR 1290 (HY000): The MySQL server is running with the --skip-grant-tables option so it cannot execute this statement
在执行上述语句后，mysql会报错，继续执行如下语句，如下
mysql> flush privileges; Query OK, 0 rows affected (0.00 sec)
再一次执行修改密码的命令，如下，
mysql> alter user root@localhost identified by ‘123456‘; Query OK, 0 rows affected (0.00 sec)
出现如上信息，说明数据库密码修改成功。
五：停止数据库的进程并登录验证数据库
停止数据库的相关进程
pkill mysqld
数据库进程结束后，马上要启动数据库
systemctl start mysqld
[root@db01 ~]#mysql -uroot -p123456 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 3 Server version: 5.7.29 MySQL Community Server (GPL) Copyright (c) 2000, 2020, 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>
由以上信息可知，数据库登录成功