不重启Mysql修改root密码的方法

一、一般忘记密码的解决办法，需要重启Mysql
1、skip-grant-tables
我们常用的方法是使用skip-grant-tables选项，mysqld server启动之后并不使用权限系统（privilege system）。用户不需要任何账号、不受任何限制的访问数据库中所有数据。为了安全起见，通常加上 skip-networking ，mysqld不侦听任何TCP/IP连接请求。操作过程如下，
1）修改my.cnf配置文件，在mysqld选项中添加skip-grant-tables和skip-networking。
2）再重启mysqld server。
3）通过sql语句修改mysql.user表中存储密码。执行flush privileges，重新启用mysql权限系统。

复制代码 代码如下:

UPDATE mysql.USER SET Password=PASSWORD('newpwd')WHERE User='root';
FLUSH PRIVILEGES;

复制代码 代码如下:

UPDATE mysql.user SET Password=PASSWORD('newpwd') WHERE User='root';
FLUSH PRIVILEGES;

复制代码 代码如下:

mysqld_safe --init-file=/home/me/mysql-init &

二、不重启mysqld的方法

1、首先得有一个可以拥有修改权限的mysql数据库账号，当前的mysql实例账号（较低权限的账号，比如可以修改test数据库）或者其他相同版本实例的账号。把data/mysql目录下面的user表相关的文件复制到data/test目录下面。

复制代码 代码如下:

[root@localhost mysql]# cp mysql/user.* test/
[root@localhost mysql]# chown mysql.mysql test/user.*

复制代码 代码如下:

[root@localhost mysql]# mysql -utest -p12345
Welcome to the MySQL monitor.  Commands end with ; or /g.
Your MySQL connection id is 17
Server version: 5.5.25a-log Source distribution

Copyright (c) 2000, 2011, 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> use test
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> update user set password=password('yayun') where user='root';
Query OK, 0 rows affected (0.00 sec)
Rows matched: 5  Changed: 0  Warnings: 0

mysql>

复制代码 代码如下:

mv mysql/user.MYD mysql/user.MYD.bak
mv mysql/user.MYI mysql/user.MYI.bak
cp test/user.MY* mysql/
chown mysql.mysql mysql/user.*

复制代码 代码如下:

[root@localhost mysql]# pgrep -n mysql
2184
[root@localhost mysql]#
[root@localhost mysql]# kill -SIGHUP 2184

复制代码 代码如下:

[root@localhost mysql]# mysql -uroot -pyayun
Welcome to the MySQL monitor.  Commands end with ; or /g.
Your MySQL connection id is 20
Server version: 5.5.25a-log Source distribution

Copyright (c) 2000, 2011, 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>