Difficult with UPDATE SQL query CI

PHP Code:
$this->forename = 'testing';
            $this->surname = 'testing';
            $this->email = 'testing';
            $this->password = 'testing';
            $this->address = 'testing';
            $this->city = 'testing';
            $this->county = 'testing';
            $this->country = 'testing';
            $this->post_code = 'testing';
            $this->access_level = 0;

            echo $id;

            $this->password = password_hash($this->password, PASSWORD_DEFAULT, ['cost' => 15]);
            $sql = "UPDATE user SET forename = ?, surname = ?, email = ?, password = ?, address = ?, city = ?, county = ?, country = ?, post_code = ?, access_level = ? WHERE id = ?";
            $this->db->query($sql, array($this->forename, $this->surname, $this->email, $this->password, $this->address, $this->city, $this->county, $this->country, $this->post_code, $this->access_level, $id));