CentOS - Install MySQL Server
Initially this tutorial explained how to install MariaDB as a drop in replacement for MySQL as CentOS does not come with MySQL in its repositories and MariaDB really is a "drop in" replacement compatibility wise. I suggest you use that tutorial unless you have any specific reason why it has to be MySQL instead of MariaDB.
I think it's worth mentioning that Debian 9 is going a step further and installing MariaDB when you use the command
sudo apt install mysql-server -y.
If I ever find out how to install MySQL server on CentOS9, then I'll be sure to put the instructions here.