i am having 3 sets of drop down list. i am trying to display the mysql table when i selected the last dropdown list. all example are shows for only one dropdown only. Help are really appreciated!! Thanks in advance. :)
This is my ajax code:
<script type="text/javascript">
function ajaxFunction()
{
var httpxml;
try
  {
  // Firefox, Opera 8.0+, Safari
  httpxml=new XMLHttpRequest();
  }
catch (e)
  {
  // Internet Explorer
  try
    {
    httpxml=new ActiveXObject("Msxml2.XMLHTTP");
    }
  catch (e)
    {
    try
      {
      httpxml=new ActiveXObject("Microsoft.XMLHTTP");
      }
    catch (e)
      {
      alert("Your browser does not support AJAX!");
      return false;
      }
    }
  }
function stateChanged() 
    {
    if(httpxml.readyState==4)
      {
//alert(httpxml.responseText);
var myObject = JSON.parse(httpxml.responseText);
for(j=document.myForm.PTT.options.length-1;j>=0;j--)
{
    document.myForm.PTT.remove(j);
}
var PTT1=myObject.value.PTT1; // ptt1 remove change to PTT only.
//var optn = document.createElement("OPTION");
//optn.text = 'Select PTT';
//optn.value = '';
document.myForm.PTT.options.add(optn);
for (i=0;i<myObject.PTT.length;i++)
    {
    var optn = document.createElement("OPTION");
    optn.text = myObject.PTT[i];
    optn.value = myObject.PTT[i];
    document.myForm.PTT.options.add(optn);
    if(optn.value==PTT1){
        var k= i+1;
        document.myForm.PTT.options[k].selected=true;
        }
    } 
//////////////////////////
for(j=document.myForm.EXT.options.length-1;j>=0;j--)
    {
        document.myForm.EXT.remove(j);
    }
    var EXT1=myObject.value.EXT1;
//alert(city1);
    for (i=0;i<myObject.EXT.length;i++)
    {
        var optn = document.createElement("OPTION");
        optn.text = myObject.EXT[i];
        optn.value = myObject.EXT[i];
        document.myForm.EXT.options.add(optn);
        if(optn.value==EXT1){
        document.myForm.EXT.options[i].selected=true;
        }
    } 
///////////////////////////
    document.getElementById("txtHint").style.background='#00f040';
    document.getElementById("txtHint").innerHTML='done';
//setTimeout("document.getElementById('txtHint').style.display='none'",3000)
    }
    }
    var url="checking2.php";
    var REGION=myForm.REGION.value;
    if(choice != 's1'){
        var PTT=myForm.PTT.value;
        var EXT=myForm.EXT.value;
            }else{
                var PTT='';
                var EXT='';
                }
    url=url+"?REGION="+REGION;
    url=url+"&PTT="+PTT;
    url=url+"&EXT="+EXT;
//url=url+"&id="+Math.random();
    myForm.st.value=PTT;
//alert(url);
    document.getElementById("txtHint2").innerHTML=url;
    httpxml.onreadystatechange=stateChanged;
    httpxml.open("GET",url,true);
    httpxml.send(null);
    document.getElementById("txtHint").innerHTML="Please Wait....";
    document.getElementById("txtHint").style.background='#f1f1f1';
}
</script>
//this is the html code
<div id="txtHint" style="width : 100px;background-color: #cccc33;">Message area</div>
    <br><br>
    <form name="myForm" action='details.php' method='post'">
    <input type=hidden name=st value=0>
    <table width=500>
    //use this function to collect the value of region from table.
    <tr><td >
    Select Region:<br><select name=REGION id='s1' onchange=ajaxFunction('s1');>
    <option value=''>Select One</option>
    <?Php
        require "config2.php";// connection to database 
        $sql="select distinct REGION from all_exchangelist ";
        foreach ($dbo->query($sql) as $row) {
        echo "<option value=$row[REGION]>$row[REGION]</option>";
            }
    ?>
</select>
</td><td ><select name=PTT  onchange=ajaxFunction('s2')>
<option value=''>Select One</option></select></td>
<td ><select name=EXT  onchange=ajaxFunction('s3')>
<option value=''>Select One</option></select></td>
</tr></tr>
<tr><td colspan=3><input type=submit value='Submit'></td></tr>
</form>
</table>
<br><br>
<div id="txtHint2"></div>
This is for validating the html and ajax code:
<?Php
include "config2.php"; // connection details
error_reporting(0);// With this no error reporting will be there
//////////
/////////////////////////////////////////////////////////////////////////////
$REGION=$_GET['REGION'];// 
$PTT1=$_GET['PTT'];
$EXT1=$_GET['EXT'];
///////////// Validate the inputs ////////////
if((strlen($REGION)) > 0 and (!ctype_alpha($REGION))){ 
echo "Data Error";
exit;
}
// Checking ptt variable (with space ) ///
if ((strlen($PTT1)) > 0 and ctype_alpha(str_replace(' ', '', $PTT1)) === false) {
echo "Data Error";
exit;
}
/////////// end of input validation //////
if(strlen($REGION) > 0){
$q_REGION="select distinct(PTT) from all_exchangelist where REGION = '$REGION'";
}else{
$q_REGION="select distinct(PTT) from all_exchangelist";
}
//echo $q_region;
$sth = $dbo->prepare($q_REGION);
$sth->execute();
$PTT = $sth->fetchAll(PDO::FETCH_COLUMN);
$q_PTT="select distinct(EXT) from all_exchangelist where ";
if(strlen($REGION) > 0){
$q_PTT= $q_PTT . " REGION = '$REGION' ";
}
if(strlen($PTT1) > 0){$q_PTT= $q_PTT . " and  PTT='$PTT1'";}
$sth = $dbo->prepare($q_PTT);
$sth->execute();
$EXT = $sth->fetchAll(PDO::FETCH_COLUMN);
$main = array('PTT'=>$PTT,'EXT'=>$EXT,'value'=>array("PTT1"=>"$PTT1","EXT1"=>"$EXT1"));
echo json_encode($main); 
?> 
