สอบถามวิธี update ตะกร้าสินค้า โดยกดปุ่ม Apply Code โดยไม่ต้องรีเฟรชหน้า

<div class="col-xs-12">
	<div class="col-xs-12">
		<div class="totalbooking brown">
			<?php
				foreach ($_SESSION[room] as $key=>$val):
					$_room = $db->GetRecord("room","roomtype='{$val[roomtype]}' AND ratecode='{$val[ratecode]}'");
					$rate = $objRate->getRateByPeriod($period[idperiod],$_room[idroom]);
			?>
					<div class="col-xs-12"><strong class="strongbooking"><?=stripslashes($_room[roomname])?></strong></div>
					<div class="col-xs-12">
						<div class="col-xs-7"><p><?=$_SESSION[room][$_room[roomtype]][rooms]?> Room(s) x <?=$diffdate?> Night(s)</p></div>
						<div class="col-xs-2"><p>THB</p></div>
						<div class="col-xs-3 text-right"><p><?= number_format($_SESSION[room][$_room[roomtype]][rooms]*$diffdate*$rate[directbooking],2)?></p></div>
					</div>
					<div class="col-xs-12">
						<div class="col-xs-7"><p>Extra Bed (<?=$_SESSION[room][$_room[roomtype]][extra]?> x <?=  $rate[extrabed]?> x <?=$diffdate?>)</p></div>
						<div class="col-xs-2"><p>THB</p></div>
						<div class="col-xs-3 text-right"><p><?= number_format($_SESSION[room][$_room[roomtype]][extra]*$diffdate*$rate[extrabed],2)?></p></div>
					</div>
					<div class="col-xs-12">
						<div class="col-xs-7">
							<strong>Discount</strong>
						</div>
						<div class="col-xs-2">
							<strong>THB</strong>
						</div>
						<div class="col-xs-3 text-right">
							<strong id="discount">0</strong>
						</div>
					</div>
					<div class="col-xs-12"><strong id="codestatus"></strong></div>
			<?
					$sum += ($_SESSION[room][$_room[roomtype]][rooms]*$diffdate*$rate[directbooking])+($_SESSION[room][$_room[roomtype]][extra]*$diffdate*$rate[extrabed]);
				endforeach;
			?>
			<div class="col-xs-12">
				<div class="col-xs-7"><h4>Total</h4></div>
				<div class="col-xs-2"><h4>THB</hh45></div>
				<div class="col-xs-3 text-right"><h4><?=number_format($sum,2);?></h4></div>
				<input type="text" hidden value="<?=$sum?>" name="sum" id="sum">
			</div>
			<div class="clearfix"></div>
		</div>
	</div>
</div>

var HttPRequest = false;
function doCallAjax() {
	HttPRequest = false;
	if (window.XMLHttpRequest) { // Mozilla, Safari,...
		HttPRequest = new XMLHttpRequest();
		if (HttPRequest.overrideMimeType) {
			HttPRequest.overrideMimeType('text/html');
		}
	} else if (window.ActiveXObject) { // IE
		try {
			HttPRequest = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				HttPRequest = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	} 
	if (!HttPRequest) {
		alert('Cannot create XMLHTTP instance');
		return false;
	}
	var url = 'AjaxDiscount.php';
	var pmeters = "tcode=" + encodeURI( document.getElementById("code").value)+
	"&tsum=" + encodeURI( document.getElementById("sum").value);
	HttPRequest.open('POST',url,true);
	HttPRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
	HttPRequest.setRequestHeader("Content-length", pmeters.length);
	HttPRequest.setRequestHeader("Connection", "close");
	HttPRequest.send(pmeters);
	HttPRequest.onreadystatechange = function() {
		if(HttPRequest.readyState == 3) { // Loading Request
			document.getElementById("discount").innerHTML = "Now is Loading...";
		}
		if(HttPRequest.readyState == 4) { // Return Request
			if(HttPRequest.responseText == '0') {
				document.getElementById("discount").innerHTML = 0;
			}
			else {
				document.getElementById("discount").innerHTML = HttPRequest.responseText;
			}
		}
	}
}

	/*** By Weerachai Nukitram ***/
	/***  http://www.ThaiCreate.Com ***/
	session_start();
	$strcode = trim($_POST["tcode"]);
	$strsum = trim($_POST["tsum"]);
	//*** Check Username ***//
	$objConnect = mysql_connect("localhost","aaaaaa","aaaaaaa") or die("Error Connect to Database");
	$objDB = mysql_select_db("aaaaaaaa");
	//*** Check Username & Password ***//
	$strSQL = "SELECT * FROM discount_code WHERE code = '".$strcode."' ";
	$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
	$objResult = mysql_fetch_array($objQuery);
	if(!$objResult){
		//echo "<div class='col-xs-12'><strong>Sorry, this voucher is not valid.</strong></div>";
		echo 0;
	}else{
		//*** Session ***//
		if($objResult["dis"] != ''){
			echo -($strsum*$objResult["dis"])/100;
		}else{
			echo -$objResult["price"];
		}
		session_write_close();
	}
	mysql_close($objConnect);