Mini Shell

<?php
require_once("../config.php");
//cookiecheck();
?>
<?php 
if(!empty($_POST['course'])){
	$course_id=$_POST['course'];
	$data=$conn->prepare("select * from subjects where course_id=$course_id");
    $data->execute();$result=$data->fetchall();
	foreach($result as $row){
		echo "<option value='$row[subject_id]'";echo">$row[subject_name]</option>";
	}
}
else{
	$subject_id=$_POST['subject'];
	$data=$conn->prepare("select * from chapters where subject_id=$subject_id");
    $data->execute();$result=$data->fetchall();
	foreach($result as $row){
		echo "<option value='$row[chapter_id]'";echo">$row[chapter_name]</option>";
	}	
}
?>