Do not enter empty field values ​​in the database. Codeigniter, how?

Question

MySQL

Good day.
It is required not to enter the data of empty fields into the database if the user has not filled in the field.
Controller:

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);
        		}
        	}
        }
    }

Model:

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);
    }

Answer 1

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