NYCPHP Meetup

[Shannon Weyrick]

Steve Manes wrote:
> Kshitij Bedi wrote:
> 
>> I have a database with zipcodes and corresponding latitudes and 
>> longitudes.
>> Can anyone suggest a mysql statement that can pull me all zipcodes 
>> within 20
>> or 50 or 100 miles of a given zipcode
> 
> 
> You can do it as an imprecise rectangle, where latitude/longitude is 
> plus/minus a certain number of minutes.  Then you just do a SELECT for 
> all zipcodes where the longitude/latitude falls within that rectangle. 
> That's what a lot of job boards do and it usually works well enough for 
> estimation, especially insofar as the longitude/latitude in those 
> zipcode databases are only rough centers of mass.  Otherwise, if you 
> need more precision you'll need to use spherical geometry, which is very 
> costly.
> 

We needed this at Roadsend awhile back. I ended up implementing the 
formula in a MySQL extension (as a function) so we could do direct 
database queries on distance, based on zipcode/lat/long columns.

Not sure about attachments on the list, so I put the source up on the web:

http://www.roadsend.com/range.cc

The first commented line is the actual command I used to compile it. 
Included in the other comments is how you can load the function into the 
server.

Hope it helps.

-------------------
Shannon Weyrick
Roadsend, Inc.

Roadsend Compiler: The Commercial PHP Implementation
www.roadsend.com