I've got a database of metropolitan areas (both in the united states and also the relaxation around the globe). The database records are pretty straight forward text strings. Presently the database consists of even small metropolitan areas (population 10,000). If only to utilize a bigger scale database rather, by setting the metropolitan areas into bigger geographicalmetropolitan areas. A good example could possibly be the Urban centers in Google's AdWords API:

http://code.google.com/intl/iw-IL/apis/adwords/docs/developer/adwords_api_us_metros.html

however i don't have any problem using other databases rather.

I'd be thankful for any suggestions about how this is often carried out using existing databasesAPIs!

You should use Yahoo's GeoPlanet database. It is simple to find what is the parent of every place (WOEID - where on the planet ID).

EDIT: You may also access this database using YQL.