thinkphp 执行sql语句，表前缀问题

<?php
return array(
	'DB_TYPE'	=>	'mysql',
	'DB_HOST'	=>	'127.0.0.1',
	'DB_NAME'	=>	'guchu',
	'DB_USER'	=> 	'root',
	'DB_PWD'	=>	'root',
	'DB_PORT'	=>	'3306',
	'DB_FREFIX' =>	'gc_',
	'DB_DSN'	=>	''
);

上边是配置文件，以为php能自动追加表前缀的呢，竟然没这个能力，只能手动加载了，如下：

public function getarticlelist(){
		$list=M("article",C('DB_FREFIX'))->select();
		echo $list[1]['title'];
	}