I like this function in PHP:

function multi_sort($array, $akey)
{
  function compare($a, $b)
  {  
     global $key;
     if ($a[$key]>$b[$key]){
         $varcmp = "1";
         return $varcmp;
     }
     elseif ($a[$key]<$b[$key]){
         $varcmp = "-1";
         return $varcmp;
     }
     elseif ($a[$key]==$b[$key]){
         $varcmp = "0";
         return $varcmp;
     }
  }
  usort($array, "compare");
  return $array;
}

You call this function like this:
$array = multi_sort($array, $key = ‘keyName’);

this will set the array to a sorted version sorted by key ascending