// coded by alex dot hristov dot 88
   function sortmulti ($array, $index, $order, $natsort=FALSE, $case_sensitive=FALSE) {
          if(is_array($array) && count($array)>0) {
              foreach(array_keys($array) as $key) 
              $temp[$key]=$array[$key][$index];
              if(!$natsort) {
                  if ($order=='asc')
                      asort($temp);
                  else    
                      arsort($temp);
              }
              else 
              {
                  if ($case_sensitive===true)
                      natsort($temp);
                  else
                      natcasesort($temp);
              if($order!='asc') 
                  $temp=array_reverse($temp,TRUE);
              }
              foreach(array_keys($temp) as $key) 
                  if (is_numeric($key))
                      $sorted[]=$array[$key];
                  else    
                      $sorted[$key]=$array[$key];
              return $sorted;
          }
      return $sorted;
  }

Very helpful function for sorting multi-dimensional arrays

Sort Multi-Dimensional Arrays

sort, array

PHP