Creating a dynamic Button for my multiple dropdown lists - php

Question

I jut created a dynamic dropdown list that are dependant on each other on Comugg.com. Heres the code.
function dropdownmenu() {
include_once "connection.php";
?>
<div class="make">
<label>Make</label>
<select name="make" id="makelist" onchange="getId(this.value);">
<option value="">Select Make</option>
<?php
$query = "select distinct(Make) from websitemasterlist order by Make ASC";
$results = mysqli_query($conn, $query);
foreach($results as $info) {
?>
<option value="<?php echo $info[Make]; ?>"><?php echo $info[Make]; ?></option>
<?php
}
?>
</select>
</div>
<div id="model">
<label>Model</label>
<select name="model" id="modellist" onchange="getId2(this.value);">
<option value="">Select Model</option>
</select>
</div>
<div id="year">
<label>Year</label>
<select name="year" id="yearlist" onchange="getId3(this.value);">
<option value="">Select Year</option>
</select>
</div>
<button id="dropdownbutton" onclick="dropdownbutton()" class="vc_general vc_btn3 vc_btn3-size-md vc_btn3-shape-rounded vc_btn3-style-3d vc_btn3-color-success">Dropdown</button>
<script>
function getId(val){
jQuery.ajax({
method: "POST",
url: "getdata.php",
data: "make="+val,
success:function(data){
jQuery("#modellist").html(data);
}
});
}
function getId2(val){
jQuery.ajax({
method: "POST",
url: "getdata.php",
data: "model="+val,
success:function(data){
jQuery("#yearlist").html(data);
}
});
}
function dropdownbutton(val){
}
</script>
<?php
}
and heres my getdata.php
<?php
include_once "connection.php";
$make = $_POST["make"];
$model= $_POST["model"];
if (!empty($_POST["make"])) {
$make = $_POST["make"];
echo $query = "SELECT Distinct Model FROM websitemasterlist where Make='".$make."'";
$results = mysqli_query($conn, $query);
?>
<option value="">Select Model</option>
<?php
foreach ($results as $info){
?>
<option value="<?php echo $info["Model"]; ?>"><?php echo $info["Model"]; ?></option>
<?php
}
}
if (!empty($_POST["model"])) {
$model = $_POST["model"];
echo $model;
echo $query = "SELECT Distinct Year FROM websitemasterlist where Model='".$model."'";
$results = mysqli_query($conn, $query);
?>
<option value="">Select Year</option>
<?php
foreach ($results as $info){
?>
<option value="<?php echo $info["Year"]; ?>"><?php echo $info["Year"]; ?></option>
<?php
}
}
?>
Im trying to figure out how to go about creating a dynamic link. For example i wanted to do something like this but i am unsure of how to get the selected values from each field.
<a href="http://comugg.com/category/<?php echo $year; ?>/<?php echo $make; ?>/<?php echo $model; ?>>text</a>
How should i go about this?