php/mysql zip code proximity search

Question

I\'m just looking for suggestions on the best way to do this...

I need to create a search function that searches for \"users\" within a 50 mile radius of a zip code

Answer 1

Start here but note that the solution isn't very fast:

PHP Zip Code Range and Distance Calculation

Now to make it fast - we are going to replace the lookup to use a spatial index :)

1. Use MySQL

2. Add a column to the database called location and make it type POINT

3. Make sure it accepts nulls right now

4. Run the following SQL Query

   UPDATE zip_code SET location = PointFromText(CONCAT('POINT(',lon,' ',lat,')'));

5. Now, make the column not accept nulls

6. Add a spatial index to the location column

7. In the code from the above project replace the function 'get_zips_in_range' with the following:

   function get_zips_in_range($zip, $range, $sort=1, $include_base) 
        {
   
   
       // returns an array of the zip codes within $range of $zip. Returns
       // an array with keys as zip codes and values as the distance from
       // the zipcode defined in $zip.
   
       $this->chronometer();                     // start the clock
   
       $details = $this->get_zip_point($zip);  // base zip details
       if ($details == false) return false;
   
       // This portion of the routine  calculates the minimum and maximum lat and
       // long within a given range.  This portion of the code was written
       // by Jeff Bearer (http://www.jeffbearer.com). This significanly decreases
       // the time it takes to execute a query.  My demo took 3.2 seconds in
       // v1.0.0 and now executes in 0.4 seconds!  Greate job Jeff!
   
       // Find Max - Min Lat / Long for Radius and zero point and query
       // only zips in that range.
       $lat = $details[0];
       $lon = $details[1];
   
       $return = array();    // declared here for scope
   
       $first = true;
       $radius = $range/69.172;
       $boundary = "POLYGON((";
       for($i=0; $i <= 360; $i += 360/24)
       {
           if($first)
           {
               $first = false;
           }
           else
           {
               $boundary .= ', ';
           }
   
           $clon = $radius*cos(deg2rad($i)) + $lon;
           $clat = $radius*sin(deg2rad($i)) + $lat;
           $boundary .= "$clon $clat" ;
       }
   
       $boundary  .= '))';
   
       $sql = "SELECT zip_code, city, county, state_name, state_prefix, area_code, time_zone, lat, lon FROM zip_code WHERE MBRContains(GeomFromText('$boundary'), location);";
   
       //echo $sql;
       $r = mysql_query($sql);
   
       if (!$r) {    // sql error
   
           $this->last_error = mysql_error();
           return false;
   
       } else {
   
           while ($row = mysql_fetch_row($r)) {
   
               // loop through the results to get the milage from src
               $dist = $this->calculate_mileage($details[0],$row[7],$details[1],$row[8]);
               if ($this->units == _UNIT_KILOMETERS) $dist = $dist * _M2KM_FACTOR;
               $return[str_pad($row[0].', '.$row[1], 5, "0", STR_PAD_LEFT)] = round($dist, $this->decimals);
   
           }
           mysql_free_result($r);
       }
   
       // sort array
       switch($sort)
       {
           case _ZIPS_SORT_BY_DISTANCE_ASC:
               asort($return);
               break;
   
           case _ZIPS_SORT_BY_DISTANCE_DESC:
               arsort($return);
               break;
   
           case _ZIPS_SORT_BY_ZIP_ASC:
               ksort($return);
               break;
   
           case _ZIPS_SORT_BY_ZIP_DESC:
               krsort($return);
               break;
       }
   
       $this->last_time = $this->chronometer();
   
       if (empty($return)) return false;
       return $return;
      }