为用户创建限制过账

我想让用户每天最多只能创建 10 个帖子。

这是我的控制器：

$id_user=$this->session->userdata('id');
$sql ="SELECT COUNT(id_post) as max_post FROM post 
WHERE post.id_user=$id_user 
AND DATE(post.time)=DATE(NOW())";
$result = $this->db->query($sql);
if ($result > 10) //line number 17
{
  //redirect to home
} elseif($result <= 10 ) //line number 20
{ 
  //then do post

然后得到这样的错误：

A PHP Error was encountered
Severity: Notice
Message: Object of class CI_DB_mysql_result could not be converted to int
Line Number: 17
A PHP Error was encountered
Severity: Notice
Message: Object of class CI_DB_mysql_result could not be converted to int
Line Number: 20

有什么答案吗？

非常感谢...