value not getting posted from the element generated by ajax class - php

Question

This is the HTML form
echo "<tr><td>Course</td><td><select name='Course' onchange='branch_selector(this.value)'>";
echo "<option value='B.Tech'>B.Tech</option>";
echo "<option value='M.Tech'>M.Tech</option>";
echo "<option value='MBA'>MBA</option>";
echo "<option value='MCA'>MCA</option>";
echo "</select></td></tr>";
echo "<tr><td><div id='branch_div_name'></div></td><td><div id='branch_div'></div></td></tr>";
this is the javascript code
function branch_selector(val) {
if(val=='B.Tech' || val=='M.Tech') {
show_name('branch_div_name','Branch');
var xmlhttp;
if (window.XMLHttpRequest)
{// code for IE7+, Firefox, Chrome, Opera, Safari
xmlhttp=new XMLHttpRequest();
}
else
{// code for IE6, IE5
xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.onreadystatechange=function()
{
if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
document.getElementById('branch_div').innerHTML=xmlhttp.responseText;
}
}
xmlhttp.open("GET","branch_selector.php",true);
xmlhttp.send();
}
else {
document.getElementById("branch_div").innerHTML="";
disappear_name('branch_div_name');
}
}
This is the PHP code running at the backened
$result = mysql_query("SELECT DISTINCT Branch FROM student_main ORDER BY Branch ASC") or die(mysql_error());
echo "<select name='Branch' id='Branch' onchange='harb()'>";
while($row = mysql_fetch_array($result)) {
if($row[0]=='' or $row[0]=='N/A') {
continue;
}
else {
echo "<option value='".$row[0]."'>".$row[0]."</option>";
}
}
echo "</select>";
The dropdown is generated without any problem. But when the form is submitted the $_POST['Branch'] is not set.
Please help

Answer 1

Ok, I have solved this issue, The solution is not the best but its getting the job done.
I am using now a hidden field and the value is this field is set according to the value of Branch of. The value is set using Javascript when user click on submit.
Its working fine, no issue whatsoever but if someone have better solution, please share.