$db->query("SELECT COUNT(*) FROM students WHERE mnumber=" . trim($_GET['mnumber']) . " AND lastblackboard=" . trim($_GET['tstamp']))->fetch(PDO::FETCH_NUM)[0] == 0) {
if( $_GET['sign'] == 0 ) {
$db->query("SELECT COUNT(*) FROM students WHERE mnumber=" . trim($_GET['mnumber']) . " AND lastblackboard=" . trim($_GET['tstamp']))->fetch(PDO::FETCH_NUM)[0] == 0) {