db_pdo_mysql::maxid PHP Method

    public function maxid($table, $field)
    {
        $sql = "SELECT MAX({$field}) AS maxid FROM `{$table}`";
        $arr = $this->find_one($sql);
        return !empty($arr) ? intval($arr['maxid']) : $arr;
    }

{
    $add = $expression ? '...	[OK]' : '...	[FAILDED]';
    echo $comment . $add . "\t\r\n";
}
define('DEBUG', 2);
define('TEST_PATH', str_replace('\\', '/', getcwd()) . '/');
define('FRAMEWORK_PATH', TEST_PATH . '../');
$conf = (include TEST_PATH . 'conf.php');
include FRAMEWORK_PATH . 'core.php';
core::init($conf);
echo "Test db_mysql.class.php \r\n\r\n";
$db = new db_pdo_mysql($conf['db']['mysql']);
$db->query("DROP TABLE IF EXISTS `bbs_user`");
$db->query("CREATE TABLE `bbs_user` (\n  `uid` int(11) unsigned NOT NULL auto_increment,\t\t# 用户id\n  `regip` int(11) NOT NULL default '0',\t\t\t\t# 注册ip\n  `regdate` int(11) unsigned NOT NULL default '0',\t\t# 注册日期\n  `username` char(16) NOT NULL default '',\t\t\t# 用户名\n  `password` char(32) NOT NULL default '',\t\t\t# 密码 md5()\n  `salt` char(8) NOT NULL default '',\t\t\t\t# 随机干扰字符，用来混淆密码\n  `email` char(40) NOT NULL default '',\t\t\t\t# EMAIL\n  `groupid` tinyint(3) unsigned NOT NULL default '0',\t\t# 用户组 id\n  `threads` mediumint(8) unsigned NOT NULL default '0',\t\t# 主题数\n  `posts` mediumint(8) unsigned NOT NULL default '0',\t\t# 回帖数\n  `avatar` int(11) unsigned NOT NULL default '0',\t\t# 头像最后更新的时间，0为默认头像\n  KEY username(`username`),\n  PRIMARY KEY (`uid`)\n) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci;");
$db->truncate('user');
$db->maxid('user-uid', 0);
$db->count('user', 0);
$db->count('user-abc-123', 100);
// 增加一条记录:
$uid = $db->maxid('user-uid', '+1');
bbs_assert("maxid('user-uid', '+1')", $uid == 1);
$r = $db->set("user-uid-{$uid}", array('username' => 'admin1', 'email' => '*****@*****.**'));
bbs_assert("set()", $r == TRUE);
// 增加一条记录:
$uid = $db->maxid('user-uid', '+1');
bbs_assert("maxid('user-uid', '+1')", $uid == 2);
$r = $db->set("user-uid-{$uid}", array('username' => 'admin2', 'email' => '*****@*****.**'));
// 增加一条记录:
$uid = $db->maxid('user-uid', '+1');
bbs_assert("maxid('user-uid', '+1')", $uid == 3);
$r = $db->set("user-uid-{$uid}", array('username' => 'admin3', 'email' => '*****@*****.**'));