Do I need to declare a property in a descendant?

Question

PHP

The question may be quite stupid, but still. Tell. In this example, is it necessary to declare a property on the heir?

class Company{

  protected $company_id = NULL;

  //обязательно нужно указать ID организации
  public function setCompany($id){
    $this->company_id = $id;
  }
  
  public function getInfo(){
    return $this->company_id;
    //... return data array company...
  }
}

class Department extends Company{

  protected $company_id = NULL; //вот тут нужно?

  public function test(){
    return $this->getInfo();
  }
}

//$a1 = new Company();
//$a1->setCompany(100);

$a2 = new Department();
$a2->setCompany(200);
echo $a2->test();

Answer 1

No, it doesn `t need.