Apply promo code or coupon code in php


index.php

<!DOCTYPE html>
<html lang="en">
<head>
  <title>Promocode apply project In PHP</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.0/js/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <h2></h2>
 
    <div class="form-group">
      <label for="email">Total Price:</label>
      <input type="text" class="form-control" id="total_price" name="total_price" value="1000.00">
    </div>
    <div class="form-group">
      <label for="promo_code">Apply Promocode:</label>
      <input type="text" class="form-control" id="coupon_code" placeholder="Apply Promocode" name="coupon_code">
	  <b><span id="message" style="color:green;"></span></b>
    </div>
    
    <button id="apply" class="btn btn-default">Apply</button>
	<button id="edit" class="btn btn-default" style="display:none;">Edit</button>
  
</div>
<script>
	$("#apply").click(function(){
		if($('#promo_code').val()!=''){
			$.ajax({
						type: "POST",
						url: "process.php",
						data:{
							coupon_code: $('#coupon_code').val()
						},
						success: function(dataResult){
							var dataResult = JSON.parse(dataResult);
							if(dataResult.statusCode==200){
								var after_apply=$('#total_price').val()-dataResult.value;
								$('#total_price').val(after_apply);
								$('#apply').hide();
								$('#edit').show();
								$('#message').html("Promocode applied successfully !");
								
							}
							else if(dataResult.statusCode==201){
								$('#message').html("Invalid promocode !");
							}
						}
			});
		}
		else{
			$('#message').html("Promocode can not be blank .Enter a Valid Promocode !");
		}
	});
	$("#edit").click(function(){
		$('#coupon_code').val("");
		$('#apply').show();
		$('#edit').hide();
		location.reload();
	});
</script>
</body>
</html>

connection.php

<?php
$url='localhost';
$username = "root";
$password = "";
$dbname = "school";
$conn = mysqli_connect($url, $username, $password, $dbname);
/* Check connection */
if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}
?>
 

process.php

  <?php
include 'conn.php';
$coupon_code=$_POST['coupon_code'];
$query=mysqli_query($conn,"select * from coupon_code where coupon_code='$coupon_code' and status=1");
$row=mysqli_fetch_array($query);
if (mysqli_num_rows($query)>0){
	echo json_encode(array(
				"statusCode"=>200,
				"value"=>$row['value']
			));
}
else{
	echo json_encode(array("statusCode"=>201));
}

?>