Javascript dynamic select

[Oldsoldier]

Hi am new to javascript.
Am trying to create dependent three dropdown select box from the database.
I have been able to manage to create the first two but can't figure out how to create the third box

$(document).ready(function() {
$('#school').change(function(){
 var code = $(this).val();
 //alert(code);
 var data = 'code='+ code;

 $.ajax({
 type: "POST",
 url:"cert.php",
 data: data,
 cache: false,
 success: function(html)
 {
   $('#cert').html(html);
 }
 });
 });

[physics]

Please provide more information, including the relevant HTML you want to work with and maybe some sample data.

[Oldsoldier]

Hi Physics
This is what i have.

Index.php
<form action="" method="post">
<select name="school" id="school"> 
<?php 
 include 'db.php';
 $sql = "SELECT DISTINCT tier_one FROM three_drops";
 $query = mysqli_query($db,$sql);
 while($row = mysqli_fetch_array($query)){
 echo '<option value="'.$row['tier_one'].'">'.$row['tier_one'].'</option>';
 }
 ?>
</select> 
</br>
<select name="cert" id="cert">
<option value="" selected="selected">Select your Certification</option>
</select>
</br>
<select name="prog" id="prog">
<option value="" selected="selected">Select your Programme</option>
</select>
</form> 

[edited by: Oldsoldier at 11:13 pm (utc) on Jan 8, 2015]

[Oldsoldier]

Ps. I changed code to code 2 because of the styling option in posting on the forum
Cert.php

<?php
include 'db.php';
if(isset($_POST['code2'])){
$sql = "SELECT DISTINCT tier_two FROM three_drops WHERE tier_one='" . $_POST[code2] . "'";
$query = mysqli_query($db,$sql);
if(mysqli_num_rows($query)==0){
echo '<option>No Records</option>';
} else {
while($row = mysqli_fetch_array($query)){
echo '<option value="' . $row['tier_two'] . '">' . $row['tier_two'] . '</option>';
}
}
}else{
echo '<option>An error Occured</option>';
}

if(isset($_POST['code1'])){
$sql = "SELECT * FROM three_drops WHERE tier_two= '" . $_POST[code1] . "'";
$query = mysqli_query($db,$sql);
if(mysqli_num_rows($query)==0){
echo '<option>No Records</option>';
} else {
while($row = mysqli_fetch_array($query)){
echo '<option value="'.$row['tier_three'].'">'.$row['tier_three'].'</option>';
}
}
}else{
echo '<option>An error Occured</option>';
}
?>

sql database
CREATE TABLE IF NOT EXISTS `two_drops` (
`id` int(11) NOT NULL auto_increment,
`tier_one` varchar(255) NOT NULL,
`tier_two` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM ;

--
-- Dumping data for table `two_drops`
--

INSERT INTO `two_drops` (`id`, `tier_one`, `tier_two`) VALUES
(1, 'Colors', 'Red'),
(2, 'Colors', 'Blue'),
(3, 'Colors', 'Green'),
(4, 'Colors', 'Yellow'),
(5, 'Colors', 'Black'),
(6, 'Shapes', 'Square'),
(7, 'Shapes', 'Circle'),
(8, 'Shapes', 'Triangle'),
(9, 'Shapes', 'Rectangle'),
(10, 'Shapes', 'Oval');