yum list installed | grep mysql
yum -y remove mysql-libs.x86_64
yum -y install mysql-server mysql mysql-devel
rpm -qi mysql-server
service mysqld start
update from 5.1 to 5.5
http://stackoverflow.com/questions/9361720/update-mysql-version-from-5-1-to-5-5-in-centos-6-2