PHP question and answers

<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content=
"width=device-width, initial-scale=1.0">
<title>
How to use a Http GET or POST for an Ajax Calls?
</title>
<script type="text/javascript">
function getTheSubCategoryList()
{
var CategoryType=document.getElementById("PrimCategory").value;

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 (this.readyState == 4 && this.status == 200)
{
var data = this.responseText;
document.getElementById("resDivId1").innerHTML = data;
document.getElementById("BTN123").disabled = false;
}
else
{
document.getElementById("BTN123").disabled = true;
}
}
xmlhttp.open("GET","ajax_second_page_GET.php?PrimCategory="+CategoryType,true);
xmlhttp.send();
}
</script>
</head>
<body>
<form name="Form1" id="Form1" autocomplete="off" method="POST" action="form_submit_process.php">
<div class="col-sm-12">
<div class="form-group col-sm-6">
<label>Category Type</label>
<select name="PrimCategory" id="PrimCategory" class="form-control" required onchange="getTheSubCategoryList()">
<option value="Vegetables">Vegetables</option>
<option value="Fruits">Fruits</option>
<option value="Flower">Flower</option>
</select>
</div>
<div class="form-group col-sm-6">
<label>Sub Category</label>
<select name="SubCategory" id="resDivId1" class="form-control">
<option value="">--select---</option>
</select>
</div>
<div class="col-sm-12">
<div class="reset-button" id="btton">
<input type="submit" id="BTN123" value="SAVE" class="btn btn-primary" name="submit" disabled="">
</div>
</div>
</div>
</form>
</body>
</html>

<?php
if ($_SERVER["REQUEST_METHOD"] == "GET")
{
if(!empty($_GET["PrimCategory"]))
{
$p_CategoryType2=rawurldecode($_GET["CategoryType"]);
if($p_CategoryType2=="Vegetables")
{
     echo "<option>Carrot</option><option>Broccoli</option><option>Spinach</option>";
}
if($p_CategoryType2=="Fruits")
{
     echo "<option>Banana</option><option>Apple</option><option>Mango</option>";
}
if($p_CategoryType2=="Flower")
{
     echo "<option>Daffodil</option><option>Sunflower</option><option>Rose</option>";
}
}
}
?>

<html>
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content=
"width=device-width, initial-scale=1.0">
<title>
How to use a Http POST for an Ajax Calls?
</title>
<script type="text/javascript">
function getSubCategory(str){
if(str) {
$.ajax({
type: "post",
url: "Ajax_Second_Page_POST.php",
data: {"PrimCategory": str},
cache: false,
success: function (data) {
$("#SubCategoryId").html(data).slideDown("slow");
}
});
} else
{
alert("Something went wrong...");
}
}
</script>
</head>
<body>
<form name="Form1" id="Form1" autocomplete="off" method="POST" action="form_submit_process.php">
<div class="col-sm-12">
<div class="form-group col-sm-6">
<label>Category Type</label>
<select name="PrimCategory" id="PrimCategory" class="form-control" required onchange="getTheSubCategoryList()">
<option value="Vegetables">Vegetables</option>
<option value="Fruits">Fruits</option>
<option value="Flower">Flower</option>
</select>
</div>
<div class="form-group col-sm-6" >
<label>Sub Category</label>
<select name="SubCategoryID" id="SubCategoryId" class="form-control">
<option value="">--select---</option>
</select>
</div>
<div class="col-sm-12">
<div class="reset-button" id="btton">
<input type="submit" id="BTN123" value="SAVE" class="btn btn-primary" name="submit" disabled="">
</div>
</div>
</div>
</form>
</body>
</html>

<?php
if(isset($_POST["PrimCategory"]))
{
$p_CategoryType2=$_POST["PrimCategory"];
if($p_CategoryType2=="Vegetables")
{
     echo "<option>Carrot</option><option>Broccoli</option><option>Spinach</option>";
}
if($p_CategoryType2=="Fruits")
{
     echo "<option>Banana</option><option>Apple</option><option>Mango</option>";
}
if($p_CategoryType2=="Flower")
{
     echo "<option>Daffodil</option><option>Sunflower</option><option>Rose</option>";
}
}
?>

AJAX GET() and POST() Methods

Example of AJAX GET() Methods

Example of AJAX POST() Methods