JSON ที่ดึงออกมาจาก Database มันซ้ำกัน ซึ่งจริงๆแล้วต้องไม่ซ้ำกัน ช่วยดูโค๊ดทีครับ

$sql = "select room.id as roomid,fl_id,roomNum,room.type,rWidth,rHeight,room_type,bu_id,fl_num from room INNEr JOIN room_type ON room.type = room_type.id INNER JOIN floor ON room.fl_id = floor.id
where floor.bu_id = '$buid' and roomNum LIKE '%$roomno%' ORDER BY bu_id asc , roomNum asc";
$q = mysql_query($sql);
$qnum = mysql_num_rows($q);
if($qnum > 0){
	$returnar = array();
	while ($row = mysql_fetch_assoc($q)) {		
		$rtype["room"]["id"] = $row["roomid"];
		$rtype["room"]["fl_id"] = $row["fl_id"];
		$rtype["room"]["roomNum"] = $row["roomNum"];
		$q_material = mysql_query("select * from relation INNER JOIN material ON material.id = relation.mat_id INNER JOIN mat_type ON mat_type.id = material.type where relation.r_id = ".$row["roomid"]." ");
		while ($rowmat = mysql_fetch_assoc($q_material)) {
			$rtype["room"]["material"][] = $rowmat["serial_number"];
		}
		array_push($returnar, $rtype);

	}
	echo stripslashes(json_encode($returnar)); 
	
}