secure database info in different environments

Hi, I have a generic database class that I built to connect to our different databases. From other posts that I've read, I think the safe thing is for me to put this file outside the web root, ensure it has a .php extension, set the include path to include this folder and include it in any pages that require it. Is this correct? Also, how do you handle the different environments: dev, test, and prod? I don't want to have to change the code every time I copy the file over. Do I have an independent file that determines if that folder should point to dev/test/prod? Thanks for your help. Regards, Bruce