Re: [SQL] Latitude / Longitude

On Thursday 12 September 2002 15:49, Tim Perdue wrote:
> On Thu, Sep 12, 2002 at 12:49:21PM -0500, Larry Rosenman wrote:
> > Look at contrib/earthdistance, I **think** it does what you need.
>
> Thanks, yeah this starts to get me into the realm of what I need. It still
> has to run every possible permutation to figure out which one is closest
> for each postalcode. What I'll do is run that once and build a 3rd table
> which can be used to join the other two together using a view.

If you are looking for everything within a certain radius of a zip code, what
I have done in the past is calculate the highest/lowest longitude and
latitude and then select anything that falls between them and only check
those ones to see if they fall within the radius.

That's saves a lot of time over checking the exact distance for every zip
code.

- James