From Fedora Project Wiki

Suppose you have installed the following packages for testing in Fedora 18: mariadb, mariadb-libs, mariadb-server

For installing MySQL packages back on your system in one transaction (so you don't loose any depended packages) you can use yum shell command as follows (without testing repository enabled anymore):

# yum shell
> remove mariadb mariadb-libs mariadb-server
> install mysql mysql-libs mysql-server
> run
> ^D