**
 * ArraySortUtil is a array sort utility, you can extends the sorting engine.
 *
 * @version 0.1
 * @package utility.sort
 */
class ArraySortUtil
{
 static function uasort($unsort, $fields)
 {
  if ( !is_array($unsort) || sizeof($unsort) <= 0 ) return $unsort;
  $sorted = uasortEngine::uasort($unsort, $fields);
  return $sorted;
 }
 static function multisort($unsort, $fields)
 {
  if ( !is_array($unsort) || sizeof($unsort) <= 0 ) return $unsort;
  $sorted = multisortEngine::multisort($unsort, $fields);
  return $sorted;
 }
}
class multisortEngine
{
 static function multisort($unsort, $fields)
 {
  $sorted = $unsort;
  if (is_array($unsort))
  {
   $loadFields = array();
   foreach($fields as $sortfield)
   {
    $loadFields["field"][] = array(
        "name" => $sortfield["field"],
        "order" => $sortfield["order"],
        "nature" => $sortfield["nature"],
        "caseSensitve" => $sortfield["caseSensitve"]
    );
    $loadFields["data"][$field["field"]] = array();
   }
   // Obtain a list of columns
   foreach ($sorted as $key => $row) {
    foreach($loadFields["field"] as $field) {
     $value = $row[$field["name"]];
     $loadFields["data"][$field["name"]][$key] = $value;
    }
   }
   $parameters = array();
   foreach($loadFields["field"] as $sortfield) {
    $array_data = $loadFields["data"][$sortfield["name"]];
    $caseSensitve = ( $sortfield["caseSensitve"] == null ) ? $sortfield["caseSensitve"] : false;
    if (!$caseSensitve) $array_data = array_map('strtolower', $array_data);
    $parameters[] = $array_data;
    if ( $sortfield["order"] != null ) $parameters[] = ( $sortfield["order"] ) ? SORT_DESC : SORT_ASC;
    if ( $sortfield["nature"] != null ) $parameters[] = ( $sortfield["nature"] ) ? SORT_REGULAR : SORT_STRING;
   }
   $parameters[] = &$sorted;
   call_user_func_array("array_multisort", $parameters);
  }
  return $sorted;
 }
}
class uasortEngine
{
 static private $caseSensitve = false;
 static private $sortfields = array();
 static private $sortorder = true;
 static private $nature = false;
 static private function uasort_callback(&$a, &$b)
 {
  foreach(self::$sortfields as $sortfield)
  {
   $_field = $sortfield["field"];
   $_order = isset($sortfield["order"]) ? $sortfield["order"] : self::$sortorder;
   $_caseSensitve = isset($sortfield["caseSensitve"]) ? $sortfield["caseSensitve"] : self::$caseSensitve;
   $_nature = isset($sortfield["nature"]) ? $sortfield["nature"] : self::$nature;
   if ($_field != "")
   {
    $retval = 0;
    if ($_nature)
    {
     if ($_caseSensitve)
     {
      $compare = strnatcmp($a[$_field], $b[$_field]);
     }
     else
     {
      $compare = strnatcasecmp($a[$_field], $b[$_field]);
     }
    }
    else
    {
     if ($_caseSensitve)
     {
      $compare = strcmp($a[$_field], $b[$_field]);
     }
     else
     {
      $compare = strcasecmp($a[$_field], $b[$_field]);
     }
    }
    if ($compare !== 0 && !$_order) $compare = ($compare > 0) ? -1 : 1;
   }
   if ($compare !== 0) break;
  }
  return $compare;
 }
 static function uasort($unsort, $fields)
 {
  self::$sortfields = $fields;
  $sorted = $unsort;
  uasort($sorted, array('uasortEngine', 'uasort_callback'));
  return $sorted;
 }
}

<?php
require_once('class.ArraySortUtil.php');
// declare test data
$assetData[] = array("id" => 1, "category"=>"Hardware", "subcategory"=>"Personal Computer", "supplier" => "DELL", "particular"=>"Vostro 1320", "purchase_price"=>2300, "other_charges"=>500);
$assetData[] = array("id" => 2, "category"=>"Hardware", "subcategory"=>"Personal Computer", "supplier" => "DELL", "particular"=>"Vostro 1420", "purchase_price"=>2500, "other_charges"=>0);
$assetData[] = array("id" => 3, "category"=>"Hardware", "subcategory"=>"Laptop", "supplier" => "DELL", "particular"=>"Vostro 1520", "purchase_price"=>4500, "other_charges"=>100);
$assetData[] = array("id" => 4, "category"=>"Hardware", "subcategory"=>"Laptop", "supplier" => "Acer", "particular"=>"Apire One", "purchase_price"=>2500, "other_charges"=>200);
$assetData[] = array("id" => 5, "category"=>"Furniture", "subcategory"=>"Table", "supplier" => "CHEN", "particular"=>"Manager Table", "purchase_price"=>1000, "other_charges"=>0);
$assetData[] = array("id" => 6, "category"=>"Furniture", "subcategory"=>"Table", "supplier" => "CHEN", "particular"=>"Staff Table", "purchase_price"=>500, "other_charges"=>0);
$assetData[] = array("id" => 7, "category"=>"Furniture", "subcategory"=>"Chair", "supplier" => "CHEN", "particular"=>"Staff Chair", "purchase_price"=>500, "other_charges"=>0);
$sorted = ArraySortUtil::multisort($assetData, array(
  array("field"=>"category"),
  array("field"=>"subcategory", "order" => true) // desc
 ));
echo "
multisort:result
";
echo "
";
 print_r($sorted);
echo "
";
$sorted = ArraySortUtil::uasort($assetData, array(
  array("field"=>"category"),
  array("field"=>"subcategory", "order" => true) // desc
 ));
echo "
uasort:result
";
echo "
";
 print_r($sorted);
echo "
";