อยากทราบการเพิ่มข้อมูล และรูปภาพ โดยใช้code ตามบทเรียน แต่ถ้าไม่อัพโหลดรูปไห้ใส่ภาพ imagenullเข้าไป

<?
// --------------------------------------------------------เพิ่มสินค้า--------------------------------------------------------
$pdctg = $_POST['hdctg'];
$pdnum = $_POST['txtnum'];
$pdname = $_POST['txtname'];
$pddetail = $_POST['txtdetail'];
$pdprice = $_POST['txtprice'];
$pdamount = $_POST['txtamount'];
$new = $_POST['slnew'];
$sale = $_POST['slsale'];
$promotion = $_POST['slpromo'];
$pdtyp = $_POST['hd_typ_id'];
$pdpic = $_POST['brw_pic'];
		
		
		$i=0;
		$sql = "SELECT MAX(pd_id) AS pd_id FROM product ";
		$result = mysql_query($sql) or die ("Query Error : MAX(pd_id) " . mysql_error());
		$record = mysql_fetch_array($result);
		$pdid = $record["pd_id"];
		$pdid +=1;
		
	//echo $totalRows_rs_table = mysql_num_rows($rs_table);
		
		if(move_uploaded_file($_FILES["filUpload"]["tmp_name"],"imageproduct/".$_FILES["filUpload"]["name"]))
	{

		//*** Insert Record ***//
		$otop = mysql_pconnect($hostname_otop, $username_otop, $password_otop) or trigger_error(mysql_error(),E_USER_ERROR); 
		$strSQL = "INSERT INTO product ";
		$strSQL .="(pd_num, pd_name, pd_detail,pd_price,pd_amount,pd_new,pd_sale,pd_promotion,pd_ctg_id,typ_id, pd_image) VALUES ('$pdnum', '$pdname', '$pddetail', '$pdprice', '$pdamount', '$new', '$sale', '$promotion', '$pdctg', '$pdtyp','imageproduct/".$_FILES["filUpload"]["name"]."')";
		$objQuery = mysql_query($strSQL);		
		
		do{
		$txtti = $_POST['txti'][$i];
		$txttable = $_POST['hdtable'][$i];
		$querypdoth = "INSERT INTO product_property_other (pd_id, pd_tb_id, pd_ctg_id, pd_detail) VALUES ('$pdid', '$txttable', '$pdctg', '$txtti')";
		   $rs_oth = mysql_query($querypdoth, $otop) or die(mysql_error());
		   
		   $i++;
		} while ($row_rs_table = mysql_fetch_assoc($rs_table));
	}		   	
	echo "<meta http-equiv='refresh' content='50;URL=admin_product_add_four.php'>";
// --------------------------------------------------------ปิดเพิ่มสินค้า--------------------------------------------------------
?>