PHP二位数组排序

    function list_sort_by($list, $field, $sortby = 'asc')
    {
        if (is_array($list))
        {
            $refer = $resultSet = array();
            foreach ($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;
    }