Utiliser des constantes dans une requête MySQL

    public function insertOrder($users_id, $product_orders, $orders_date, $orders_numero, $orders_status)
    {
        define('En preparation', 1);

        $req = $this->pdo->prepare("
                                    INSERT INTO orders 
                                    SET users_id = :users_id, product_orders = :product_orders, orders_date = :orders_date, orders_numero = :orders_numero, orders_status= :1
                                   ");
        $req->execute(["users_id" => $users_id, "product_orders" => $product_orders, "orders_date" => $orders_date, "orders_numero" => $orders_numero, "orders_status" => $orders_status]);

    }