<?php
$form_flight_id = filter_input(INPUT_POST, "flight_id", FILTER_SANITIZE_STRING);
$form_class_name = filter_input(INPUT_POST, "class_name", FILTER_SANITIZE_STRING);
<?php
$form_flight_id = filter_input(INPUT_POST, "flight_id", FILTER_SANITIZE_STRING);
$form_class_name = filter_input(INPUT_POST, "class_name", FILTER_SANITIZE_STRING);