var xmlHttp;
function createXMLHttpRequest()
{
	 if(window.XMLHttpRequest)
	{
			xmlHttp = new XMLHttpRequest();//FF
	}
	else if(window.ActiveXObject)
	{
			 try
			{
					xmlHttp = new ActiveX0bject("Msxml2.XMLHTTP");//IE5
			}
			catch(e)
			{}
			try
			{
					xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");//IE6
			}
			catch(e)
			{}
			if(!xmlHttp)
			{
					window.alert("error");
					return false;
			}
	}
}
function Requeststage(stage)
{

				createXMLHttpRequest();
				xmlHttp.open("GET","dynamicstage.php?stage="+stage,true);
				xmlHttp.onreadystatechange = handlestageChange;
				xmlHttp.send(null);
}
function handlestageChange()
{
		if(xmlHttp.readyState==4)
		{
				document.getElementById("class").innerHTML = 'loading.......';
				if(xmlHttp.status==200)
				{
					document.getElementById("class").innerHTML = xmlHttp.responseText;
					Requestsubject(document.getElementById('subject').value);
				}
 		}
}
function Requestsubject(subject)
{
				var stage=document.form1.stage.value;
				createXMLHttpRequest();
				encodeURIComponent(subject);
				xmlHttp.open("GET","dynamicsubject.php?subject="+subject+"&stage="+stage,true);
				xmlHttp.onreadystatechange = handlesubjectChange;
				xmlHttp.send(null);
}
function handlesubjectChange()
{
		if(xmlHttp.readyState==4)
		{
				document.getElementById("abs").innerHTML = 'loading.......';
				if(xmlHttp.status==200)
				{
					document.getElementById("abs").innerHTML = xmlHttp.responseText;
					Requestcourse(document.getElementById('semester').value);
				}
 		}
}
function Requestcourse(semester)
{
				var stage=document.form1.stage.value;
				var subject=document.form1.subject.value;
				createXMLHttpRequest();
				xmlHttp.open("GET","dynamiccourse.php?subject="+subject+"&stage="+stage+"&semester="+semester,true);
				xmlHttp.onreadystatechange = handlecourseChange;
				xmlHttp.send(null);
}
function handlecourseChange()
{
		if(xmlHttp.readyState==4)
		{
				document.getElementById("crsdisplay1").innerHTML = 'loading.......';
				if(xmlHttp.status==200)
				{
					document.getElementById("crsdisplay1").innerHTML = xmlHttp.responseText;
					document.getElementById("crsdisplay2").innerHTML = xmlHttp.responseText;
					document.getElementById("crsdisplay3").innerHTML = xmlHttp.responseText;
					document.getElementById("crsdisplay4").innerHTML = xmlHttp.responseText;
					document.getElementById("crsdisplay5").innerHTML = xmlHttp.responseText;
				}
 		}
}

//dynamicsubject.php
<?php
header('Content-Type:text/html;charset=UTF-8');
require_once('Connections/MyOcy.php');
if($_GET["subject"]!="")
		{
		$data=$_GET["stage"];
		$data2=$_GET["subject"];
		$sql_str="select * from p_data where subject='".$data2."'and nid like '%V$data%'";
		$result = mysql_query($sql_str,$MyOcy) or die(mysql_error());
		$array = mysql_fetch_array($result);
		$row = mysql_num_rows($result);
		$i=1;
		while($i<$row){
								$array= mysql_fetch_array($result);
								$i++;
        						echo
								'<div class="adline">
        						<div class="sid">'.$array[nid].'</div>
        						<div class="sname">'.$array[name_ch].'</div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
       							<div class="per1"><input type="checkbox" value=""></div>
        						<div id="per2"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div id="per2"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div>
        						<div class="per1"><input type="checkbox" value=""></div><br class="clear"/></div>';
		}
		}
		else
		echo '';
?>