1. 查看centos版本号：

lsb_release -a

2. 查看mysql服务是否开机启动：

http://www.cnblogs.com/panjun-Donet/archive/2010/08/10/1796873.html

chkconfig --list |grep mysqld

mysqld          0:off   1:off   2:off   3:off   4:off   5:off   6:off

chkconfig mysqld on

chkconfig --list|grep mysqld

mysqld          0:off   1:off   2:on    3:on    4:on    5:on    6:off

3. 修改mysql root用户密码

update mysql.user set password=password('xxxx') where user='root';

flush privileges;