二维数组根据某个键排序

  function list_sort_by($list, $field, $sortby = 'asc')
    {
      if (is_array($list))
      {
        $refer = $resultSet =[];
        foreach ($list as $i => $data)
        {
          $refer[$i] = &$data[$field];
        }
        switch ($sortby)
        {
          case 'asc': // 正向排序
            asort($refer);
            break;
          case 'desc': // 逆向排序
            arsort($refer);
            break;
          case 'nat': // 自然排序
            natcasesort($refer);
            break;
        }
        foreach ($refer as $key => $val)
        {
          $resultSet[] = &$list[$key];
        }
        return $resultSet;
      }
      return false;
    }