Refreshing dynamic drop down options - php

Question

I got 3 drop down boxes dependent on each other when selected. For e.g. if I select a type from drop down 1, then drop down 2 populates only the options relevant to what i select from the first drop down box. The 3rd drop down is dependable on the 2nd drop down option.
The problem i am facing is that the options on the drop down boxes are not refreshing when i want to choose something different.
Can anyone help me?
This is my form:
<label>Tour Type </label>
<select id="tourtype" name="tourtype" required>
<option value="" selected="selected">--Select--</option>
<?php
$sql=mysql_query("Select tour_type_id,tour_name from tour_type");
while($row=mysql_fetch_array($sql))
{
$tour_type_id=$row['tour_type_id'];
$name=$row['tour_name'];
echo "<option value='$tour_type_id'>$name</option>";
}
?>
</select>
<label>Country</label>
<select id="country" name="country" class="country" required>
<option value="" selected="selected">-- Select --</option>
</select>
<label>Destination</label>
<select id="destination" name="destination" class="destination" required>
<option value="" selected="selected">-- Select --</option>
</select>
This is the js at the bottom of the form:
<script>
$('#tourtype').change(function () {
var id = $(this).val();
$.ajax({
type: "POST",
url: "ajax.php",
data: {
id: id,
get_countries: 1
},
success: function (html) {
$("#country").empty();
$("#country").append(html);
},
error: function () {
alert("ajax failed");
}
});
});
$('#country').change(function () {
var id = $(this).val();
$.ajax({
type: "POST",
url: "ajax.php",
data: {
id: id,
get_destination: 1
},
success: function (html) {
$("#destination").empty();
$("#destination").append(html);
},
error: function () {
alert("ajax failed");
}
});
});
</script>
Finally this is the ajax.php
<?php
include('../config.php');
if ($_REQUEST['get_countries']) {
$sql = mysql_query("SELECT * FROM `countries` WHERE `tour_type_id`=" . $_REQUEST['id']);
$countries = "";
while ($row = mysql_fetch_array($sql)) {
$cid = $row['countries_id'];
$name = $row['countries_name'];
$countries .= "<option value='" . $cid . "'>" . $name . "</option>";
}
echo $countries;
} elseif ($_REQUEST['get_destination']) {
$destination = "";
$sql = mysql_query("SELECT * FROM `destination` where `country_id` =" . $_REQUEST['id']);
while ($row = mysql_fetch_array($sql)) {
$destination_id = $row['destination_id'];
$name = $row['destination_name'];
$destination .= "<option value='" . $destination_id . "'>" . $name . "</option>";
}
echo $destination;
}
?>

Answer 1

I have fixed the problem. Just had to add more data to the 3 separate tables where my query is fetching the data from