[RESOLVED] [2005] Geographic data

Anyone have any experience of consulting some kind of mapping database that provides information about a 'location'?

For example, on online web shopping basket forms, the user can enter a zip code and their address is populated from that, usually only the house number is needed to fully determine an address.

On Ebay, it's possible to specify a radius from a location and presumably determine the roads/streets that lie within that radius, or whether a zip code is within that radius.

How is this achieved?

They do this with the help of a GeoCoding database such as Google Maps or Yahoo. Check out Yahoo's Geocoding API here for a good example.

This database converts addresses into lat/long coordinates. After that, it's simple math. In the Ebay example, Ebay knows your lat/long, and it knows the lat/long of all the people selling products, so it just runs them through a simple equation to get the distance; as you would the points of a line and filters out all the ones over XX distance.

Hope that is what you're looking for.

That's exactly it. Thanks.