i have writeen following query in my code.
$tquery="SELECT questions.id,questions.date,questions.title,users.user_name,subjects.subject FROM questions INNER JOIN users ON questions.student_id=users.id INNER JOIN topics ON questions.topic_id=topics.id INNER JOIN subjects ON topics.subject_id=subjects.id WHERE subjects.id=".$_SESSION['sub1']." OR subjects.id=".$_SESSION['sub2'].";";
but when i am trying to echoing its result it is not displaying anything.