Views in post

Hi guys, I'm looking at Codeigniter these days and I'll need your help.

I have this class that is nothing but the display of every single page, but I needed to enter a query, where every access was updated to the field "views" in the database.

PHP Code:

   public function get_post($slug = FALSE) {
        if ($slug === FALSE) {
            $query = $this->db->get('post');
            return $query->result_array();
        }
        $query = $this->db->get_where('post', array('slug' => $slug));
        return $query->row_array();
    } 


I've added a query that add +1 to the view field, but obviously does not count. So I need to +1 the current value of the field views.

PHP Code:

   public function get_post($slug = FALSE) {
        if ($slug === FALSE) {
            $query = $this->db->get('post');
            return $query->result_array();
        }
        $query = $this->db->get_where('post', array('slug' => $slug));

        $this->views = +1;
        $this->db->update('post', $this, array('slug' => $slug));

        return $query->row_array();
    } 


My question is, how can I get the current value of the field views from the database so that the variable is moved to +1? I hope I'm well explained, I'm using Google Translate, I'm Italian.
Thanks!