在知道原始密码的情况下

[root@web1 ~]# mysqladmin -uroot -p -S /home/mysql/3307/mysql.sock password "brian123"   # 要修改的密码

Enter password:123456

# 测试

[root@web1 ~]# mysql -uroot -p -S /home/mysql/3307/mysql.sock

Enter password:123456

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

[root@web1 ~]# mysql -uroot -p -S /home/mysql/3307/mysql.sock

Enter password:brian123

[root@web1 ~]# mysql -uroot -p -S /home/mysql/3307/mysql.sock

Enter password:

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 6

Server version: 5.7.23 MySQL Community Server (GPL)

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>

# 登录数据库修改密码

update mysql.user set authentication_string=password('123qwe') where user='root' and Host = 'localhost';

alter user 'root'@'localhost' identified by '123';

set password for 'root'@'localhost'=password('123');

# 一定记得刷新权限，不然不生效

flush privileges;

# 数据库密码忘记了

PS：在单实例的情况下我们是可以停掉数据库的，但是在多实例的情况下没有密码是停不了的，只能用kill 来停的

# 使用kill停止不记得密码的数据库

[root@web1 ~]# ps aux | grep 3306 | awk '{print $2}' |xargs kill

# 使用mysqld_safe 加参数绕过认证

PS： 我用的是多实例的，根据实际情况修改下面的路径就行

[root@web1 ~]# /usr/local/mysql/bin/mysqld_safe --defaults-file=/home/mysql/3306/my.cnf --user=mysql --skip-grant-tables &

[root@web1 ~]# netstat -lntup | grep 3306

tcp6       0      0 :::3306                 :::*                    LISTEN      57475/mysqld

# 现在就是没有密码可以登录了

[root@web1 ~]# mysql -uroot -p -S /home/mysql/3306/mysql.sock

Enter password:                                                     # 这一步直接回车

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 2

Server version: 5.7.23 MySQL Community Server (GPL)

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>

# 进来以后再修改密码

mysql> update mysql.user set authentication_string=password('123qwe') where user='root' and Host = 'localhost';

Query OK, 1 row affected, 1 warning (0.00 sec)

Rows matched: 1  Changed: 1  Warnings: 1

mysql> flush privileges;

Query OK, 0 rows affected (0.00 sec)

mysql>

# 停掉MySQL重新启动 这次不用指定--skip-grant-tables参数了

[root@web1 ~]# ps aux | grep 3306 | awk '{print $2}' |xargs kill

[root@web1 ~]# /usr/local/mysql/bin/mysqld_safe --defaults-file=/home/mysql/3306/my.cnf --user=mysql &

[root@web1 ~]# mysql -uroot -p -S /home/mysql/3306/mysql.sock

Enter password: 123qwe

Welcome to the MySQL monitor.  Commands end with ; or \g.

Your MySQL connection id is 2

Server version: 5.7.23 MySQL Community Server (GPL)

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>