thinkphp 小弟我执行了一条更新语句 想要获取到影响的行数

$book = M('Book');
$data = array();
$data['shengCunQi'] = time();
$book->save($data,array('where'=>"shengcunqi = '0000-00-00 00:00:00'",'limit'=>'17'));
//我想获取到这条语句所影响到的行数. 
也就是说: 我要获取到 我一共更新了多少条语句.

$book = M('Book');
$data = array();
$data['shengCunQi'] = time();
$result = $book->save($data,array('where'=>"shengcunqi = '0000-00-00 00:00:00'",'limit'=>'17'));
var_dump($result); //$result将返回你所影响的行数或false