I am developing a store locater; the thing i am looking for is a database of the United states Zip codes.... so that is a zip code doesn't have a store... it can show results from nearby zip codes.. Around 10 to 50 miles near. let me know? Thanks.
let me understand, are you looking for a Zip code database or php script to find nearest store based on a zip code from the database you already have?
Until you find the information you need, you might try what I did for a client. The script I wrote just uses simple subtraction to determine the five closest matches between the user's Zip Code and that of the store locations. That was good enough for my situation since it was for locating matches among a relatively small number of regional distributors and not a large number of stores, but it might be sufficient until you can make the tool you want.
Get the google maps API up and running. You can retrieve Geo coordinates from them and compare those to check ranges of nearby stores. As their public API is limited to a certain amount of request per day (i think 15.000) it may be handy to store the Geo results locally.
Sign up at google www google com/maps Start playing with a single request to return geo coordinates. Then get two points on a map and tune your distance calculation. I suggest indexing the store addresses available and calculate range from those. The google and business indexes aren't complete for that matter. ps. soz for the link, i'm not allowed to post yet.