Radius and Zipcodes

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Thread: Radius and Zipcodes

  1. #1
    Join Date
    Dec 1969

    Default Radius and Zipcodes

    I have databse with all the zip codes in the US.<BR>How can I build a function that can calculate radius from a certain zip code?<BR><BR>Thanks!

  2. #2
    Join Date
    Dec 1969

    Default Several long discussions on this...

    ...in the past. Let me see if I can find a good one.<BR><BR>Yeah, here&#039;s one:<BR>http://www.aspmessageboard.com/forum/showMessage.asp?F=27&M=710170&P=1#709712<BR><BR>If you implement every one of the suggestions I made in that thread, you&#039;d have a system that should be efficient enough even if you are using Access.<BR><BR>The big tricks are:<BR>(1) *avoid* doing the radius calculation except for the zip codes that are within reasonable "range."<BR>(2) store the latitude and longitude in a form that is "friendly" to your calculations (miles work pretty well).<BR>(3) if you are going after the more accurate calculation (and I *still* think it&#039;s a waste of time and coding to do so, but...), then store the SIN() and COS() values in the DB, so they don&#039;t have to be calculated each time.<BR><BR><BR>

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