how to retrieve data using dropdown from database using ajax on same page

[mukeshrasm]

hello i want to display the subjects on the same page based on class selected by user.

i am using dropdown for classes. so when user will select a particular class then it will display subjects in the same page based on class from database.

i am giving my code along with so please tell me the error.

code for database

<?php
include "database.php";
$class1= $_GET['q'];
$selectclass= "SELECT Subjects FROM subjects WHERE Class= '$class1'";
$query=mysql_query($selectclass); 
echo "<table>";
echo"<tr>";
echo"<th> Subjects</th><th>Marks</th></tr>";
while($rows=mysql_fetch_array($query))
{
    echo "<tr>";
    echo "<td>";
    echo $rows['Subjects'];
    echo "</td>";
    echo "<td>";
    echo "<input type= text/>";
    echo "</td>";
    echo "</tr>";
 
}
echo "</table>";
?>
 
 

code for javascript file

var xmlHttp;
function selectClass(str)
{
    alert(str);
    xmlHttp=GetXmlHttpObject()
    if(xmlHttp==null)
    {
        alert("Error");
        return 
    }
    var url="getsubject.php";
    url=url+"?q"=str;
    //url=url+"&sid="+Math.random();
    xmlHttp.onreadystatechange=stateChanged
    xmlHttp.open("GET",url,true)
    xmlHttp.send(null)
}
 
function stateChanged() 
    { 
        if (xmlHttp.readyState==4|| xmlHttp.readyState=="complete")
        { 
        document.getElementById("txtselect").innerHTML=xmlHttp.responseText;
        }
    }
 
function GetXmlHttpObject()
{
    var xmlHttp=null;
    try
      {
      xmlHttp=new XMLHttpRequest();
      }
    catch (e)
      {
      try
        {
        xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
        }
      catch (e)
        {
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
        }
      }
    return xmlHttp
}
 

i have called javascript file in the header section. i have also used <div element with id txtselect>

but value is not coming and not showing any error as well..I think the value for $class1 is not coming that's why it is showing nothing.

please help me out.

[Atli]

Hi. Welcome to TSDN!

What does the alert(str) show you?
Have you made sure the PHP script works and prints out the expected results? (By navigating to it in your browser)

[ak1dnar]

http://yourdomain/getsubject.php?q=set_the_value_here
First, execute the server page directly like this. Then you can find where the issue is.