修改MySQL的登录设置：

在[mysqld]的段中加上一句：skip-grant-tables
例如：
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
skip-name-resolve
skip-grant-tables
保存并且退出vi。
3．重新启动mysqld

/etc/init.d/mysqld restart

Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]
4．登录并修改MySQL的root密码

/usr/bin/mysql

Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 3 to server version: 3.23.56
Type ‘help;’ or ‘h’ for help. Type ‘c’ to clear the buffer.
mysql> USE mysql ;
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 ( ‘new-password’ ) WHERE User = ‘root’ ;
Query OK, 0 rows affected (0.00 sec)
Rows matched: 2 Changed: 0 Warnings: 0
mysql> flush privileges ;
Query OK, 0 rows affected (0.01 sec)
mysql> quit
Bye
5．将MySQL的登录设置修改回来

vi /etc/my.cnf

将刚才在[mysqld]的段中加上的skip-grant-tables删除
保存并且退出vi。
6．重新启动mysqld

/etc/init.d/mysqld restart

Stopping MySQL: [ OK ]
Starting MySQL: [ OK ]

mysql安装
Centos 6.x 安装Mysql笔记
找到对应的源文件（注意：Centos 6.x 需要使用 EL6- 的源文件，例如：mysql57-community-release-el6-11.noarch.rpm）
https://dev.mysql.com/downloads/repo/yum/

下载源文件

wget http://dev.mysql.com/get/mysql57-community-release-el6-11.noarch.rpm

添加yum源

yum localinstall mysql57-community-release-el6-11.noarch.rpm

安装

yum install mysql-community-server

启动mysql服务

service mysqld start

设置root用户密码

set password for 'root'@'localhost'=password('123456!');

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