$ sudo apt-get update
$ sudo apt-get install freeradius-mysql 

freeradius-mysql is installed in your system.

Make ensure the freeradius-mysql package were installed using the commands given below,

$ sudo dpkg-query -l | grep freeradius-mysql *

You will get with freeradius-mysql package name, version, architecture and description in a table

freeradius-mysql package basic information: