You will need to first download and then add the MySQL repository and then update:
sudo rpm -ivh mysql-community-release-el7-5.noarch.rpm
Then install MySQL as usual and start the service. During installation, you will be asked if you want to accept the results from the .rpm file’s GPG verification. If no error or mismatch occurs, enter y.
yum install mysql-server
systemctl start mysqld
To check if MySQL is running, run:
systemctl status mysqld
You can also run the mysqlsecureinstallation script to address several security concerns in a default MySQL installation.
You will be given the choice to change the MySQL root password, remove anonymous user accounts, disable root logins outside of localhost, and remove test databases. It is recommended that you answer yes to these options.
Hope this helps!