A simple User class

// The DataLayer to MySQL
require_once $_SERVER["DOCUMENT_ROOT"] . "/api/DAL/classes/User.dal.php";

class User
{
    public $id;
    public $name;
    public $age;

    public function __construct($id = null)
    {
        $this->dl = new UserDAL();

        // Get an existing user object
        if (!empty($id)) {
            $user       = $this->getUsers($id);
            $this->id   = $user->id;
            $this->name = $user->name;
            $this->age  = $user->age;
        }
    }

    public function create($user)
    {
        // Create new user
        $this->name = $user->name;
        $this->age  = $user->age;
        return $this->dl->create($user);
    }

    public function update($user)
    {
        // Update existing user
        $this->id   = $user->id;
        $this->name = $user->name;
        $this->age  = $user->age;
        return $this->dl->update($user);
    }

    public function delete($user)
    {
        // Create new user
        $this->id = $user->id;
        return $this->dl->delete($user);
    }

    public function getUsers($id)
    {
        return $this->dl->getUsers($id);
    }

}

// Some tests...

// Get existing user
$existing_user = new User("1");
var_dump($existing_user);

// Create a new user
$new_user = new User();
$new_user->age = 23;
$new_user->name = "Bob";
$new_user->create($new_user);
var_dump($new_user);

// Update existing user
$update_user = new User();
$update_user->id = "1";
$update_user->name = "Henry";
$update_user->age = 100;
$update_user->update($update_user);
var_dump($update_user);

// Delete a user
$delete_user = new User();
$delete_user->delete("1");

$this->dl = new UserDAL();