Question

I am trying to output results of 2 sql queries to one JSON file. The problem is that I would like to order them ascending by distance which is the result of equation that takes homelat and homelon from the users table and lat, lng from locations table.(basically it takes lattitude and longitude of one point and another and computes the distance between these points). Is it possible to take some parameters from both select queries, compute it and output the result in ascending order?

$wynik = mysql_query("SELECT homelat, homelon FROM users WHERE guid='2'") or 
die(mysql_error()); ;

$query = "SELECT * FROM locations WHERE timestamp";
$result = map_query($query);
$points = array();

while ($aaa = mysql_fetch_assoc($wynik)) {

while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {

    array_push($points, array('name'=>$row['name'], 'lat'=>$row['lat'], 
'lng'=>$row['lng'], 'description'=>$row['description'], 
'eventType'=>$row['eventType'], 'date'=>$row['date'],
        'isotime'=>date('c', ($row['timestamp'])), 'homelat'=>$aaa['homelat'], 
'homelon'=>$aaa['homelon']));

}
echo json_encode(array("Locations"=>$points));

Answer 1

So the resulting array should be something like:

'name' => 'something',
'lat' => 'something',
'lng' => 'something',
'description' => 'something',
etc.

Use usort to sort it.

usort($array, 'sortByOption');
function sortByOption($a, $b) {
  $distA = dist($a['homelat'], $a['homelong'], $a['lat'], $a['long']);
  $distB = dist($b['homelat'], $b['homelong'], $b['lat'], $b['long']);
  return strcmp($distA, $distB);
}
function dist($x1, $y1, $x2, $y2) {
  return pow($x2 - $x1, 2) + pow($y2 - $y1, 2);
}

EDIT: Sorry, didn’t 100% read your question. Revised for the solution (though not a great one). You should be calculating distance in the array itself. And to save time, don’t do the square-root.

EDIT 2: Final result.

while ($aaa = mysql_fetch_assoc($wynik)) {
  while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
    array_push($points, array('name'=>$row['name'], 
                               'lat'=>$row['lat'], 
                               'lng'=>$row['lng'], 
                       'description'=>$row['description'], 
                         'eventType'=>$row['eventType'],
                              'date'=>$row['date'],
                           'isotime'=>date('c', ($row['timestamp'])), 
                           'homelat'=>$aaa['homelat'], 
                           'homelon'=>$aaa['homelon'],
                          'dist'=>dist($aaa['homelat'], $aaa['homelon'], $row['lat'], $row['lng'])
    ));
  }
}
usort($points, 'sortByDist'); // This sorts the points!
echo json_encode(array("Locations"=>$points));
function sortByDist($a, $b) {
  return strcmp($a['dist'], $b['dist']);
}
function dist($x1, $y1, $x2, $y2) {
  return pow($x2 - $x1, 2) + pow($y2 - $y1, 2);
}