Help with distance calculation

Anon

OK, I know this may sound like some easy problem that can be solved with a little thought but I seem to have writers block except with my coding and setup.

Problem:

I have a MySql DB, having information relating to certain service providers in my area... including company name, address, zipcode, latitude and longitude (to be used for distance calculations)

Problem 2:

How would I go about writing a query for such:

Approximate distance in miles = sqrt(x x + y y)

where

x = 69.1 (zip2.lat - zip1.lat)
and
y = 53 (zip2.lon - zip1.lon)

Where zip1 would be the customer zip and zip 2 the zip of some service provider and I want to return those that provide the particular service that are closest to the customer.

Problem 3:

Would I need two seperate tables of information for this calculation?

Should my select be using a while statement with the formula as the conditional?

Please help... I am so confused at this point that no amount of thought on my part is making sense. Thanks so much David

Anon

Are you trying to do this?

$query = "SELECT latitude, longitude FROM tbl WHERE companyName = 'some company'";
$result = mysql_query($query, $con);
$row = mysql_fetch_array($result);

// client's coordinates - you'll get them from somewhere
$zip1_lat = 10;
$zip1_lon = 10;

$distance = sqrt(pow($zip1_lat - $row['latitude'], 2) + pow($zip1_lon - $row['longitude'],2));

Diego

Anon

Well, I see what you are trying to do... In my application though... this is the initial starting info that I have:

the customers zip code as $czip

So, I guess what I am asking is how can I take that bit of information... and call their latitude and longitude to be used in the calculation along with the comparison to the providers latitude and longitude as I only want those results that are within say 20 miles to be returned and displayed.

I was thinking I could call an array of providers zips, latitudes, and longitudes and iterate through the array with the formula.

Maybe my question is actually can I make 2 calls to the DB for different queries on the same page as long as they are assigned to different variables? and then Iterate through the provider array withing the formula?