[quote]I am trying to upgrade my phpBB2 installation to phpBB3.
For that I need to know the location of the mySQL file.
I know I can address it by mysql.domainname.com, but where is the mySQL database file physically located??[/quote]
Since the MySQL databases are on separate machines than the web servers, and you don’t get access to these machines, you can’t access the files.
You will need to export the databases tables and then import them instead using phpMyAdmin (or login to shell user on your web server or use a local install of mysql for command-line export/import)