How to use own map database to display map on a website and use that map to find route and do other stuff ?
I recently implemented something like this. I realize it is an old question but Google has the javascript api v3 out for Google Maps and it works great.
https://developers.google.com/maps/articles/phpsqlajax_v3
This page helped me implement the entire system. Works great. You can also use php to update and edit the entries on the map.
You need xml pages and others but here is the map html page just to give you an idea of the javascript it entails.
PHP/MySQL & Google Maps Example