Zip Locator - find dealers

[casbboy]

Ok, I know how to do the formulations to find the distance between to zip codes by using their latitude and longitude points. However, that is all I know how to do.

I have a database with all zip codes and corresponding latitude and longitude points. I want to create a search on my site that finds closest 'dealers'.

Such as put in your zip,,,, choose 10, 20, or 30 miles radius and then run the search of zip codes that fall within that range.

However, I do not know how to create the coding that allows the search to grab all the zip codes (due to lat/lon) that fall within the distance. Is the program gonna have to run through my database of thousands of zips and try everyone???

I'm stuck, any suggestions or tutorials are greatly appreciated.

Thanks
Ryan

[leatherback]

Hi,

You do have lat/lon's?
Then you can of course subset first.. You select the lat/lon of current zipcode.
Next you say.. Which lat /lon coord are straight East, West, North, South at * mile distance. This would define a lat/lon block within which you have to find matches. Then you would only have to try zipp-codes within that block of data. Still.. Not nice. But better?
Especialy if you are talking about dealers, you probably don't have one on every zipp-code (?) so I supose you end up with a few hundred (?) calculations for a local search?

J.

[casbboy]

Thanks for help, but I really don't know what that means.

True however, that I do not have that many dealers so that would make work slightly easier for calculations. So, with each dealer there would have to be included the zip and lat/lon. However, if number of dealers went high then can become troublesome.

Thanks
Ryan