1、导入第三方源webtatic
rpm -Uvh http://repo.webtatic.com/yum/centos/5/latest.rpm
2、如果已安装低版本的mysql就删除
yum remove mysql mysql-*
3、安装libmysqlclient15
yum install libmysqlclient15 --enablerepo=webtatic
4、安装mysql5.5
yum install mysql55 mysql55-server --enablerepo=webtatic
5、启动并升级mysql
service mysqld start
mysql_upgrade