老师在不

$title = trim(input('post.title'));

$site = $this->db->table('sites' )->where(array('names'=>'site'))->item();

if(!$site){

$this->; db->table('sites')->insert(array('names'=>'site','values'=>json_encode($title)));

}else{

$value['values'] = json_encode($title);

$this->db->table('sites')->where(array('names) '=>'site'))->update($value);

}