php 数组根据某字段值排序

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;
}