First, to set up the yum repository, install the webtatic-release RPM based on your CentOS/RHEL release:
Webtatic EL6 for CentOS/RHEL 6.x
Webtatic EL5.1 for CentOS/RHEL 5.x:
If you already have MySql client or server installed (rpm -q mysql mysql-server), then you can upgrade using the following method:
“yum install mysql” is only there to make sure yum-plugin-replace can resolve dependencies correctly if only mysql-server was installed.
Otherwise, to install MySql client and server, then run:
You should upgrade existing tables before setting the server to become a production machine, which can be done by starting the server and running the mysql_upgrade script (this may take time depending on the size of the database).
from : https://webtatic.com/packages/mysql55/
another simple command upgrade all packages : yum upgrade
another method
To list Old MySql
yum list installed | grep -i mysql
To remove Old MySql
yum remove mysql mysql-*
Remi Dependency on CentOS 6 and Red Hat (RHEL) 6
rpm -Uvh http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm
rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
Install MySQL server
yum --enablerepo=remi,remi-test install mysql mysql-server
To list New MySql
yum list installed | grep -i mysql
start MySql server
/etc/init.d/mysqld start
## use restart after updateOR
service mysqld start
## use restart after updatechkconfig --levels 235 mysqld on
Last
mysql_upgrade -u root -p
from : http://stackoverflow.com/questions/9361720/update-mysql-version-from-5-1-to-5-5-in-centos-6-2
nilo