Why is the value assigned to a class variable not saved?

Question

PHP

Good afternoon. I continue to delve into OOP, and I am faced with the fact that I do not fully understand the essence of getters and setters.
There is a class:

class Forms {
    private $insertID = '';

public function __construct() {
        // подключение своему классу для работы с PDO (db_pdo.php)
        try {
            require_once 'c:\xampp\htdocs\EnginePHP\class\db_pdo.php';
            $this->myPDO = new DB_PDO();
        } catch(Exeption $e) {
            echo "Ошибка создания класса";
        }
        //
    }
// возвращаем ID вставленной записи
    public function getID() {
        return $this->insertID;
    }

    // устанавливаем ID вставленной записи
    public function setID($insert) {
        $this->insertID = $insert;
    }

    // вывод city и установка префикса
    public function outCity() {
        require 'c:\xampp\htdocs\EnginePHP\polls\city10.php';

        // получаем ID города по префиксу
    if (@$_REQUEST['select']) {
        $data = array($_REQUEST['select']);
        $pref = $this->myPDO->selectWhere("SELECT `id` FROM `city` WHERE `prefix` = ?", $data);
        $id_city = implode('', $pref);

        // вставляем первую запись, получаем номер первой записи, для дальнейшего обновления по номеру записи
        $data = array( 'date_start' => date("Y-m-d H:i:s"), 'id_city' => $id_city );
        var_dump($data);
        $result = $this->myPDO->insert("INSERT INTO `result` (date_start, id_city) values (:date_start, :id_city)", $data);
        if ($result) {
            $this->setID($result);
        } else {
            echo "Insert error!";
        }
        var_dump($this->getID());
    }
    }


    // вывод school с префиксом
    public function outSchool() {
        require 'c:\xampp\htdocs\EnginePHP\polls\school20.php';

            // получаем id текущей записи и обновляем выбор пользователя - школа
        if (@$_REQUEST['select1']) {
            $id = $this->getID();
            var_dump($id); 
            $id_school = ($_REQUEST['select1']);
            $data = array( 'id_school' => $id_school, 'id' => $id );
            var_dump($data); 

            $result = $this->myPDO->update("UPDATE `result` SET `id_school` = :id_school WHERE `id` = :id", $data);
            if ($result == 0) {
                echo "Update error!";
            }
        }
    
    }

    // вывод первой части опроса
    public function outOpros1() {
        require 'c:\xampp\htdocs\EnginePHP\polls\opros30.php';
        $id = $this->getID();
        var_dump($id);
        $age = $_REQUEST['ages'];
        $own = $_REQUEST['familys'];
        $clas = $_REQUEST['clasC'];
        $data = array ('age' => $age, 'own' => $own, 'class' => $clas, 'id' => $id );

        $this->myPDO->update("UPDATE `result` SET `age` = :age, `own` = :own, `class` = :class WHERE `id` = :id", $data);

    }

}

When I insert a record, everything is fine with me, the ID of this record is returned. In the next method, I have to update the record for this ID, but already in the getID () method it is empty. I don't understand. For example, to use prefixes, I use exactly the same getters and setters, everything works. Requests are checked, everything works if instead of a getter slip the usual number of IDs. And the main thing is that it doesn't give any errors, it's just that there is a $this->insertID property, and now it's empty...

Answer 1

It's impossible to look at this shit code, my eyes are bleeding.
Let's get started
1. Read about class autoloading
2. Stop writing require in methods and read about dependency injection .
3. Stop using the @ dog where it is not required. Namely, in the if (@$_REQUEST['select']) condition, there are isset and empty functions for this.
4. Clearly formulate your question without a bunch of this near-working code and write a small class describing problems with getters and setters.