``
$config = array(
                 'login' => array(
                                    array(
                                            'field' => 'login',
                                            'label' => 'Login',
                                            'rules' => 'required'
                                         ),
                                    array(
                                            'field' => 'password',
                                            'label' => 'Password',
                                            'rules' => 'required'
                                         )
                                    ),
                 'register' => array(
                                    array(
                                            'field' => 'name_r',
                                            'label' => 'Name',
                                            'rules' => 'required|alpha'
                                         ),
                                    array(
                                            'field' => 'lastname_r',
                                            'label' => 'Lastname',
                                            'rules' => 'required|alpha'
                                         ),
                                    array(
                                            'field' => 'login_r',
                                            'label' => 'Login_r',
                                            'rules' => 'required|callback_rule'
                                         ),
                                    array(
                                            'field' => 'password_r',
                                            'label' => 'Password_r',
                                            'rules' => 'required|min_length[4]|max_length[12]'
                                         ),
                                    array(
                                            'field' => 'confirm_password_r',
                                            'label' => 'Confirm_password',
                                            'rules' => 'required|matches[password_r]'
                                         ),
                                    array(
                                            'field' => 'email_r',
                                            'label' => 'Email',
                                            'rules' => 'required|valid_email'
                                         ),
                                    array(
                                            'field' => 'adres_r',
                                            'label' => 'Adres',
                                            'rules' => 'required'
                                         )
                                    ),
                                );``

Model:
``      public function register($data_db)
        {
            $this->db->where('login',$data_db['login']);
            $query = $this->db->get('users');
            $row = $query->row();
            if($row->login)
            {
            $this->form_validation->set_message('rule', 'Error Message');
            }
            else
            {
                $this->db->insert('users', $data_db);
            }``