Distance Between Postal Codes

[Dave \IT\]

I'm looking to find out how I'd go about setting up a database where a
visitor to my site could punch in their postal code, and find out how far
they are from another postal code. For example, AutoTrader has this feature
I believe to tell you how far the vehicle is from you. Dating sites have
them so you can do proximity searches.

Anyone have any ideas where I could start? I'm thinking the post office,
but if anyone else has suggestions, I'm open to hear them.

Thanks!

[David Portas]

Re: Distance Between Postal Codes

Are you in the UK? Royal Mail has some address database products that
may meet your requirements:

http://www.royalmail.com/portal/rm/shop?catId=9300091&pageId=shp_prdlist&category=cat40085&gear=shop

Other solutions exist too:

http://www.google.co.uk/search?biw=992&hl=en&q=postcode+location&btnG=Google+Search&meta=cr%3DcountryUK%7CcountryGB

--
David Portas
SQL Server MVP
--

[--CELKO--]

Re: Distance Between Postal Codes

This company does mailing list software with that data in it:

http://www.melissadata.com/Lookups/

[Dave \IT\]

Re: Distance Between Postal Codes

Actually, no, I'm in North America (Canada). Sorry for not mentioning that.

"David Portas" <REMOVE_BEFORE_ REPLYING_dporta s@acm.org> wrote in message
news:1120060282 .670987.93490@g 14g2000cwa.goog legroups.com...[color=blue]
> Are you in the UK? Royal Mail has some address database products that
> may meet your requirements:
>
> http://www.royalmail.com/portal/rm/s...0085&gear=shop
>
> Other solutions exist too:
> http://www.google.co.uk/search?biw=9...UK%7CcountryGB
>
> --
> David Portas
> SQL Server MVP
> --
>[/color]

[Terri]

Re: Distance Between Postal Codes

Be aware of the limitations of these calculations. I have done something
similar with US zipcodes, same principle. Each zone has a latitude and
longitude associated with it. This point is known as a centroid which is a
representative point for the whole zone. If the zone is a square or a circle
the centroid would be right in the middle. For a very irregular zone the
centroid might not even be in the zone. Think of a doughnut shaped zone.

Then you calculate the distance between the 2 centroids. Imagine 2 100 mile
square zones side by side. The distance calculation would be 100 miles. The
2 interested parties could actually be across the street from each other
each in their own zone.