Incorrect integer value: '$id_ML' for column `log_bd`.`order_list`.`id_ML` at row 1 what is the error?

Question

PHP

Good evening!
faced such problem:
I have a form which has to write down the received data from the user in a DB.
I made the form, the request was written, it is presented below, but nothing works, the database is connected, previously there were other requests that work fine, I checked the request in phpmyadmin in the console, everything works, I can’t understand anything (I’m attaching a screenshot of the error itself and the database below).

$id_ML = $_POST['id_ML'];
$id_customer = $_POST['id_customer'];
$id_TC = $_POST['id_TC'];
$date_order = $_POST['date_order'];
$level_order = $_POST['level_order'];
$price_order = $_POST['price_order'];
$db_table = "order_list";

$query_5 = 'INSERT INTO `order_list` (`id_ML`, `id_customer`, `id_TC`, `date_order`, `level_order`, `price_order`) VALUES ( "$id_ML", "$id_customer", "$id_TC", "$date_order", "$level_order", "$price_order")';
$result_5 = mysqli_query($connect,$query_5) or die("Not connected" . mysqli_error($connect));

Answer 1

$id_ML = $_POST['id_ML'];
$id_ML is an invalid integer variable.