That depends how your database is structured. You need to have some sort of spatial index that tells you which zip codes are close to other zip codes.
I dont know, maybe you can just use the first 3-4 digits of a zip code, but that probably wont be very accurate when dealing with areas that cross state or county lines.
What you essentially doing is 'geocoding' which is a sophisticated way of computer mapping of an address and you may well need some specific GIS software for this task, such as that made by ESRI ( WWW.ESRI.COM/, they make a product called ArcIMS that can be used to build customized webpages with any web based language (including ASP), but its not cheap.
Last edited by gfunkera; 04-19-2006 at 05:36 PM..
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