Не заносить пустые значения поля в БД. Codeigniter, как?

public function settings(){ 
       	$this->load->model('Users_Model');
    	$id = $this->session->userdata('id');
    	$this->data['get'] = $this->Users_Model->getuser($id);
		$password = $this->_clean($this->input->post('password', FALSE));
		$email 	  = $this->_clean($this->input->post('email'));
		$year 	  = $this->_clean($this->input->post('year'));

		if($password == ''){
            return $this->load->view('user/settings', $this->data);
        } else {
        	$this->form_validation->set_rules('password', 'Password', 'xss_clean');
        	$this->form_validation->set_rules('email', 'Email', 'xss_clean|trim');
        	$this->form_validation->set_rules('year', 'Year', 'xss_clean|required');
        	if($this->form_validation->run() === FALSE){
        		$this->data['msg'] = $this->pfunc->error_msg('Введенные вами данные не могут быть обновлены, т.к они не являются валидными.');
        		return $this->load->view('user/settings', $this->data);
        	} else {
        		if($this->Users_Model->update($id, $password, $email, $year)){
        			$this->data['msg'] = $this->pfunc->error_msg('Данные не были обновлены.');
        			return $this->load->view('user/settings', $this->data);
        		} else {
                    $this->data['msg'] = $this->pfunc->success_msg('Пользователь обновлен!');
                    return $this->load->view('user/settings', $this->data);
        		}
        	}
        }
    }

public function update($id, $password, $email, $year){
        $arr = array(
                        'password'  => sha1(md5($password)), 
                        'email'     => $email, 
                        'year'      => $year
                     );
        $this->db->where('id', $id);
        $this->db->update('users', $arr);
    }