เปลี่ยนค่าในโค้ดติดต่อดาต้าเบส ทำแบบไหนได้บ้างครับ

$id_work = 20;
$id_class = 2;
$strSQL3 = "
	SELECT * FROM status_work INNER JOIN student_user 
	ON student_user.id_std=status_work.id_std_ws 
	WHERE status_work.id_works = '$id_work' 
	AND status_work.id_class = '$id_class'
	ORDER BY student_user.number_std ASC
	";

$id_work = 20;
$id_class = 2;
$strSQL3 = "
	SELECT * FROM status_work INNER JOIN student_user 
	ON student_user.id_std=status_work.id_std_ws 
	WHERE status_work.id_works = '".$id_work."' 
	AND status_work.id_class = '".$id_class."'
	ORDER BY student_user.number_std ASC
	";