PHP Shopping Cart Tutorial – Step By Step Guide!

Previously, we learned how to create, read, update and delete database records on our PHP OOP CRUD tutorial. Today, we will put that knowledge to work by building a simple PHP shopping cart application.

This post will have the following contents:

1.0 Overview
2.0 Source code output preview
3.0 File structure

4.0 Prepare the database
4.1 Database design
4.2 Create MySQL tables
4.3 Database connection file
4.4 Output

5.0 Prepare the user interface
5.1 Create header layout file
5.2 Create footer layout file
5.3 Create navigation.php
5.4 Add custom CSS
5.5 Output

6.0 Display products
6.1 Create products.php
6.2 Include PHP classes
6.3 Create "product" object file
6.4 Create "product image" object file
6.5 Create "cart item" object file
6.6 Connect to the database
6.7 Initialize action and pagination
6.8 Request data from the database
6.9 Add "read" and "count" methods
6.10 Template to display products
6.11 Add "readFirst()" method
6.12 Add "exists()" method
6.13 Create pagination file
6.14 Output

7.0 How to count items in the cart?
7.1 Display count in navigation bar
7.2 Cart item count() method
7.3 Output

8.0 How to add to cart?
8.1 Make "add to cart" button work
8.2 Create add_to_cart.php
8.3 Put create() method
8.4 Create cart.php
8.5 Display message based on action
8.6 Display cart items
8.7 Put read() method in cart item object
8.8 Read products by IDs
8.9 Output

9.0 How to update cart?
9.1 Update cart quantity with JavaScript
9.2 PHP script to update cart
9.3 Update cart item in database
9.4 How to remove product from cart?
9.5 Put delete() method
9.6 Create the checkout page
9.7 Create place_order.php
9.8 Delete all items in the cart
9.9 Output

10.0 How to make the product page?
10.1 Create product.php
10.2 Read product details
10.3 Read one product method
10.4 Display message based on action
10.5 Display product thumbnails
10.6 Read images related to product
10.7 Display product image
10.8 Make image hover work
10.9 Display product details
10.10 Render 'Cart' button
10.11 Output

11.0 What People Say About This Code?
12.0 Download the LEVEL 1 Source Code
13.0 Download the LEVEL 2 Source Code
14.0 Download the PHP Shopping Cart Module
15.0 Download the PHP Shopping Cart SYSTEM

16.0 What's Next?
17.0 Related Tutorials
18.0 Notes

1.0 Overview

This is good news for you. If you do not want to use cookies or sessions for storing cart items, you can use your MySQL or MariaDB database.

Will there be any advantage if we use this approach?

One advantage I can think of is, the user can view his cart items in different computers or devices.

If we will compare it to using PHP sessions or cookies, we can say the following:

• PHP sessions can maintains the cart items only when the browser is opened. It means a user will lose his cart items once he closes his browser or turns off his computer.
• PHP cookies can maintain the cart items on one device or computer, event if the user turn his computer on and off.

The source codes in this page is NOT for you if:

• You are an already an expert in PHP & MySQL programming.
• You have a lot of time to code a shopping cart system from scratch.
• You are not that interested in learning PHP & MySQL programming.

But, this SOURCE CODE is FOR YOU if:

• You want to SAVE huge amount of development time.
• You want to develop your own shopping cart system from scratch.
• You determined to learn how to make a web application in PHP & MySQL.

But if you are an expert in PHP & MySQL programming and would like to take a look at our code, please do so! We'd love to hear your response and great insights! The comments section below is always open for anyone with questions and suggestions.

2.0 Source Code Output Preview

Below are some screenshots of our script’s output. You can click an image to view the larger version of it. Use the left and right arrow to navigate through the screenshots.

Please note that the following images are just output previews. New features might be added already the time you are reading this.

Note: If the output preview is in video format, please click the play button instead.

2.1 LEVEL 1 Source Code Output

[espro-slider id=6652]

2.2 LEVEL 2 Source Code Output

[espro-slider id=6622]

2.3 PHP Shopping Cart Module Output

[espro-slider id=6839]

The LEVEL 2 and PHP Shopping Cart Module outputs proves that you can add and customize more features. It's easier and faster if you will learn by following our tutorial below.

Downloading our source codes is your huge advantage as well. For now, let's proceed to the step by step tutorial of our LEVEL 1 source code. Enjoy!

3.0 File Structure

The following folders and files are included in the source code. It will have more meaning if you will see the code inside the folders and files.

├─ config/
├─── database.php
├─ dev/
├─── shop_cart_mysql_1.sql
├─── readme.txt
├─ images/
├─ libs/
├─── css/
├────── bootstrap/
├─── js/
├────── jquery.js
├─ objects/
├─── cart_item.php
├─── product_image.php
├─── product.php
├─ uploads/
├─── images/
├─ .htaccess
├─ add_to_cart.php
├─ cart.php
├─ checkout.php
├─ layout_foot.php
├─ layout_head.php
├─ navigation.php
├─ paging.php
├─ place_order.php
├─ product.php
├─ products.php
├─ read_products_template.php
├─ remove_from_cart.php
├─ update_quantity.php

4.0 Prepare the database

4.1 Database Design

Our database name is "shop_cart_mysql_1", and we will have three (3) tables.

4.2 Create MySQL Tables

You may run the following SQL queries on our "shop_cart_mysql_1" database.

Create the products table. This table will hold products record.

CREATE TABLE IF NOT EXISTS `products` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(512) NOT NULL,
  `description` text NOT NULL,
  `price` decimal(10,2) NOT NULL,
  `created` datetime NOT NULL,
  `modified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=latin1 COMMENT='products that can be added to cart' AUTO_INCREMENT=41 ;

Create product_images table. This table will hold images related to product.

CREATE TABLE IF NOT EXISTS `product_images` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `product_id` int(11) NOT NULL,
  `name` varchar(512) NOT NULL,
  `created` datetime NOT NULL,
  `modified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COMMENT='image files related to a product' AUTO_INCREMENT=105 ;

Create cart_items table. This table will hold cart items of our user.

CREATE TABLE IF NOT EXISTS `cart_items` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `product_id` int(11) NOT NULL,
  `quantity` double NOT NULL,
  `user_id` int(11) NOT NULL,
  `created` datetime NOT NULL,
  `modified` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 AUTO_INCREMENT=40 ;

The products and product_images table will not fully work without the sample data and images in the "/uploads/images/" directory.

You'll have to download the SQL and image files. Use the download button below. What will you get? A ZIP file with shop_cart_mysql_1.sql and 28 image files inside (1.30 MB).

Once downloaded, you may import the SQL file using PhpMyAdmin. Put the image files in "/uploads/images/" directory. You are now one step closer to the output shown in section 2.1 above.

4.3 Database connection file

Create "config" folder and inside it, create "database.php" file with the following code.

<?php
// used to get mysql database connection
class Database{

	// specify your own database credentials
	private $host = "localhost";
	private $db_name = "shop_cart_mysql_1";
	private $username = "root";
	private $password = "";
	public $conn;

	// get the database connection
	public function getConnection(){

		$this->conn = null;

		try{
			$this->conn = new PDO("mysql:host=" . $this->host . ";dbname=" . $this->db_name, $this->username, $this->password);
		}catch(PDOException $exception){
			echo "Connection error: " . $exception->getMessage();
		}

		return $this->conn;
	}

}
?>

4.4 Output

Output screenshots are coming soon!

5.0 Prepare the user interface

Layout files are needed so we can use the same header and footer code.

5.1 Create header layout file

Create layout_head.php file and place the the following code.

<!DOCTYPE html>
<html lang="en">
<head>

    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">

    <title><?php echo isset($page_title) ? $page_title : "The Code of a Ninja"; ?></title>

    <!-- Latest compiled and minified Bootstrap CSS -->
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />

    <!-- custom css for users -->
    <link href="libs/css/user.css" rel="stylesheet" media="screen">

</head>
<body>

	<?php include 'navigation.php'; ?>

    <!-- container -->
    <div class="container">
        <div class="row">

        <div class="col-md-12">
            <div class="page-header">
                <h1><?php echo isset($page_title) ? $page_title : "The Code of a Ninja"; ?></h1>
            </div>
        </div>

5.2 Create footer layout file

Create layout_foot.php file and place the following code.

		</div>
		<!-- /row -->

	</div>
	<!-- /container -->

<!-- jQuery (necessary for Bootstrap's JavaScript plugins) -->
<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
  
<!-- Latest compiled and minified Bootstrap JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
 
<!-- custom script will be here -->

</body>
</html>

5.3 Create navigation.php

The "layout_head.php" will not work without the navigation.php file. Create that file and put the following code inside.

<!-- navbar -->
<div class="navbar navbar-default navbar-static-top" role="navigation">
	<div class="container">

		<div class="navbar-header">
			<button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
			<span class="sr-only">Toggle navigation</span>
			<span class="icon-bar"></span>
			<span class="icon-bar"></span>
			<span class="icon-bar"></span>
			</button>
			<a class="navbar-brand" href="products.php">XYZ Webstore</a>
		</div>

		<div class="navbar-collapse collapse">
			<ul class="nav navbar-nav">

				<!-- highlight if $page_title has 'Products' word. -->
				<li <?php echo strpos($page_title, "Product")!==false ? "class='active'" : ""; ?>>
					<a href="products.php">Products</a>
				</li>

				<li <?php echo $page_title=="Cart" ? "class='active'" : ""; ?> >
					<a href="cart.php">
						<!--later, we'll put a PHP code here that will count items in the cart -->
						Cart <span class="badge" id="comparison-count">0</span>
					</a>
				</li>
			</ul>

		</div><!--/.nav-collapse -->

	</div>
</div>
<!-- /navbar -->

5.4 Add Custom CSS

Inside "libs/css" directory, create user.css with the following code inside it.

.text-align-center{ text-align:center; }
.f-w-b{ font-weight:bold; }
.display-none{ display:none; }

.w-5-pct{ width:5%; }
.w-10-pct{ width:10%; }
.w-15-pct{ width:15%; }
.w-20-pct{ width:20%; }
.w-25-pct{ width:25%; }
.w-30-pct{ width:30%; }
.w-35-pct{ width:35%; }
.w-40-pct{ width:40%; }
.w-45-pct{ width:45%; }
.w-50-pct{ width:50%; }
.w-55-pct{ width:55%; }
.w-60-pct{ width:60%; }
.w-65-pct{ width:65%; }
.w-70-pct{ width:70%; }
.w-75-pct{ width:75%; }
.w-80-pct{ width:80%; }
.w-85-pct{ width:85%; }
.w-90-pct{ width:90%; }
.w-95-pct{ width:95%; }
.w-100-pct{ width:100%; }

.m-t-0px{ margin-top:0px; }
.m-b-10px{ margin-bottom:10px; }
.m-b-20px{ margin-bottom:20px; }
.m-b-30px{ margin-bottom:30px; }
.m-b-40px{ margin-bottom:40px; }

.stock-text {
    font-weight: bold;
    color: #008a00;
}

.stock-text-red{
    font-weight:bold;
    color:#b12704;
}

.product-detail {
    font-weight: bold;
    margin: 0 0 5px 0;
}

.blueimp-gallery>.prev, .blueimp-gallery>.next{ border:none; }

.update-quantity-form {
    width: 150px;
    float: left;
    margin: 0 10px 0 0;
}

.cart-row {
    border-bottom: thin solid #f1f1f1;
    overflow: hidden;
    width: 100%;
    padding: 20px 0 20px 0;
}

.product-link{
    color:#000000;
}

.product-link:hover{
    color:#000000;
    text-decoration:none;
}

.product-img-thumb {
    margin: 0 0 10px 0;
    width: 100%;
    cursor: pointer;
}

6.0 Display Products

6.1 Create products.php

Now we are going to start displaying products from the database. Create products.php with the following basic code.

<?php
// set page title
$page_title="Products";

// page header html
include 'layout_head.php';

// contents will be here 

// layout footer code
include 'layout_foot.php';
?>

6.2 Include PHP Classes

Put the following code after the opening "php" tag of the previous section.

// connect to database
include 'config/database.php';

// include objects
include_once "objects/product.php";
include_once "objects/product_image.php";
include_once "objects/cart_item.php";

// connect to database here

6.3 Create "product" object file

Create "objects" folder. Inside it, create product.php file with the following code.

<?php
// 'product' object
class Product{

	// database connection and table name
	private $conn;
	private $table_name="products";

	// object properties
	public $id;
	public $name;
	public $price;
	public $description;
	public $category_id;
	public $category_name;
	public $timestamp;

	// constructor
	public function __construct($db){
		$this->conn = $db;
	}
}

6.4 Create "product image" object file

Create product_image.php file inside "objects" folder.

<?php
// 'product image' object
class ProductImage{

	// database connection and table name
	private $conn;
	private $table_name = "product_images";

	// object properties
	public $id;
	public $product_id;
	public $name;
	public $timestamp;

	// constructor
	public function __construct($db){
		$this->conn = $db;
	}
}

6.5 Create "cart item" object file

Create cart_item.php file inside "objects" folder.

<?php
// 'cart item' object
class CartItem{

    // database connection and table name
    private $conn;
    private $table_name = "cart_items";

    // object properties
    public $id;
    public $product_id;
    public $quantity;
    public $user_id;
    public $created;
    public $modified;

	// constructor
    public function __construct($db){
        $this->conn = $db;
    }
}

6.6 Connect to the database

Replace "// connect to database here" comment in products.php file with the following code.

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$product = new Product($db);
$product_image = new ProductImage($db);
$cart_item = new CartItem($db);

6.7 Initialize action and pagination

Put the following code after the code on the previous section.

// to prevent undefined index notice
$action = isset($_GET['action']) ? $_GET['action'] : "";

// for pagination purposes
$page = isset($_GET['page']) ? $_GET['page'] : 1; // page is the current page, if there's nothing set, default is page 1
$records_per_page = 6; // set records or rows of data per page
$from_record_num = ($records_per_page * $page) - $records_per_page; // calculate for the query LIMIT clause

6.8 Request data from the database

Request data from the database. Put the following code after the code on the previous section.

// read all products in the database
$stmt=$product->read($from_record_num, $records_per_page);

// count number of retrieved products
$num = $stmt->rowCount();

// if products retrieved were more than zero
if($num>0){
	// needed for paging
	$page_url="products.php?";
	$total_rows=$product->count();

	// show products
	include_once "read_products_template.php";
}

// tell the user if there's no products in the database
else{
	echo "<div class='col-md-12'>";
    	echo "<div class='alert alert-danger'>No products found.</div>";
	echo "</div>";
}

6.9 Add "read" and "count" methods

The previous section will not work without the following code inside "objects/product.php" object file.

// read all products
function read($from_record_num, $records_per_page){

	// select all products query
	$query = "SELECT
				id, name, description, price 
			FROM
				" . $this->table_name . "
			ORDER BY
				created DESC
			LIMIT
				?, ?";

	// prepare query statement
	$stmt = $this->conn->prepare( $query );

	// bind limit clause variables
	$stmt->bindParam(1, $from_record_num, PDO::PARAM_INT);
	$stmt->bindParam(2, $records_per_page, PDO::PARAM_INT);

	// execute query
	$stmt->execute();

	// return values
	return $stmt;
}

// used for paging products
public function count(){

	// query to count all product records
	$query = "SELECT count(*) FROM " . $this->table_name;

	// prepare query statement
	$stmt = $this->conn->prepare( $query );

	// execute query
	$stmt->execute();

	// get row value
	$rows = $stmt->fetch(PDO::FETCH_NUM);

	// return count
	return $rows[0];
}

6.10 Template to display products

The previous section won't work without "read_products_template.php", so create that file and put the following code.

<?php 
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
	extract($row);

	// creating box
	echo "<div class='col-md-4 m-b-20px'>";

		// product id for javascript access
		echo "<div class='product-id display-none'>{$id}</div>";

		echo "<a href='product.php?id={$id}' class='product-link'>";
			// select and show first product image
			$product_image->product_id=$id;
			$stmt_product_image=$product_image->readFirst();

			while ($row_product_image = $stmt_product_image->fetch(PDO::FETCH_ASSOC)){
				echo "<div class='m-b-10px'>";
					echo "<img src='uploads/images/{$row_product_image['name']}' class='w-100-pct' />";
				echo "</div>";
			}

			// product name
			echo "<div class='product-name m-b-10px'>{$name}</div>";
		echo "</a>";

		// product price and category name
			echo "<div class='m-b-10px'>";
				echo "$" . number_format($price, 2, '.', ',');
			echo "</div>";

			// add to cart button
			echo "<div class='m-b-10px'>";
				// cart item settings
				$cart_item->user_id=1; // we default to a user with ID "1" for now
				$cart_item->product_id=$id;

				// if product was already added in the cart
				if($cart_item->exists()){
					echo "<a href='cart.php' class='btn btn-success w-100-pct'>";
						echo "Update Cart";
					echo "</a>";
				}else{
					echo "<a href='add_to_cart.php?id={$id}&page={$page}' class='btn btn-primary w-100-pct'>Add to Cart</a>";
				}
			echo "</div>";



	echo "</div>";
}

include_once "paging.php";
?>

6.11 Add "readFirst()" method

Add "readFirst()" method in "objects/product_image.php" file. The previous section will not work without it.

// read the first product image related to a product
function readFirst(){

	// select query
	$query = "SELECT id, product_id, name
			FROM " . $this->table_name . "
			WHERE product_id = ?
			ORDER BY name DESC
			LIMIT 0, 1";

	// prepare query statement
	$stmt = $this->conn->prepare( $query );

	// sanitize
	$this->id=htmlspecialchars(strip_tags($this->id));

	// bind prodcut id variable
	$stmt->bindParam(1, $this->product_id);

	// execute query
	$stmt->execute();

	// return values
	return $stmt;
}

6.12 Add "exists()" method

Open /objects/cart_item.php and add the following method. This method checks if an item is already added to cart or not.

// check if a cart item exists
public function exists(){

    // query to count existing cart item
    $query = "SELECT count(*) FROM " . $this->table_name . " WHERE product_id=:product_id AND user_id=:user_id";

    // prepare query statement
    $stmt = $this->conn->prepare( $query );

    // sanitize
	$this->product_id=htmlspecialchars(strip_tags($this->product_id));
    $this->user_id=htmlspecialchars(strip_tags($this->user_id));

	// bind category id variable
	$stmt->bindParam(":product_id", $this->product_id);
    $stmt->bindParam(":user_id", $this->user_id);

    // execute query
    $stmt->execute();

    // get row value
    $rows = $stmt->fetch(PDO::FETCH_NUM);

    // return
    if($rows[0]>0){
        return true;
    }

    return false;
}

6.13 Create pagination file

The previous section won't work without the paging.php file. Create paging.php with the following code.

<?php
echo "<div class='col-md-12'>";

    echo "<ul class='pagination m-b-20px m-t-0px'>";

    // button for first page
    if($page>1){
        echo "<li><a href='{$page_url}' title='Go to the first page.'>";
            echo "First Page";
        echo "</a></li>";
    }

    $total_pages = ceil($total_rows / $records_per_page);

    // range of links to show
    $range = 2;

    // display links to 'range of pages' around 'current page'
    $initial_num = $page - $range;
    $condition_limit_num = ($page + $range)  + 1;

    for ($x=$initial_num; $x<$condition_limit_num; $x++) {

        // be sure '$x is greater than 0' AND 'less than or equal to the $total_pages'
        if (($x > 0) && ($x <= $total_pages)) {

            // current page
            if ($x == $page) {
                echo "<li class='active'><a href=\"#\">$x <span class=\"sr-only\">(current)</span></a></li>";
            }

            // not current page
            else {
                echo "<li><a href='{$page_url}page=$x'>$x</a></li>";
            }
        }
    }

    // button for last page
    if($page<$total_pages){
        echo "<li>";
            echo "<a href='" . $page_url . "page={$total_pages}' title='Last page is {$total_pages}.'>";
                echo "Last Page";
            echo "</a>";
        echo "</li>";
    }

    echo "</ul>";
echo "</div>";
?>

6.14 Output

Output screenshots are coming soon!

7.0 How to count items in the cart?

7.1 Display count in navigation bar

Open navigation.php and change this line:

<!--later, we'll put a PHP code here that will count items in the cart -->
Cart <span class="badge" id="comparison-count">0</span>

to this:

<a href="cart.php">
	<?php
	// count products in cart
	$cart_item->user_id=1; // default to user with ID "1" for now
	$cart_count=$cart_item->count();
	?>
	Cart <span class="badge" id="comparison-count"><?php echo $cart_count; ?></span>
</a>

7.2 Cart item count() method

Open /objects/cart_item.php and put the count() method.

// count user's items in the cart
public function count(){

    // query to count existing cart item
    $query = "SELECT count(*) FROM " . $this->table_name . " WHERE user_id=:user_id";

    // prepare query statement
    $stmt = $this->conn->prepare( $query );

    // sanitize
    $this->user_id=htmlspecialchars(strip_tags($this->user_id));

    // bind category id variable
    $stmt->bindParam(":user_id", $this->user_id);

    // execute query
    $stmt->execute();

    // get row value
    $rows = $stmt->fetch(PDO::FETCH_NUM);

    // return
    return $rows[0];
}

7.3 Output

Output screenshots are coming soon!

8.0 How to add to cart?

8.1 Make "add to cart" button work

Put the following code before ending "body" tag of layout_foot.php file.

<script>
$(document).ready(function(){
	// add to cart button listener
	$('.add-to-cart-form').on('submit', function(){

		// info is in the table / single product layout
		var id = $(this).find('.product-id').text();
		var quantity = $(this).find('.cart-quantity').val();

		// redirect to add_to_cart.php, with parameter values to process the request
		window.location.href = "add_to_cart.php?id=" + id + "&quantity=" + quantity;
		return false;
	});
});
</script>

8.2 Create add_to_cart.php

Create add_to_cart.php file because when 'Add to cart' button was clicked, that file with the following code inside will be executed.

<?php
// parameters
$product_id = isset($_GET['id']) ? $_GET['id'] : "";
$quantity = isset($_GET['quantity']) ? $_GET['quantity'] : 1;

// make quantity a minimum of 1
$quantity=$quantity<=0 ? 1 : $quantity;

// connect to database
include 'config/database.php';

// include object
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$cart_item = new CartItem($db);

// set cart item values
$cart_item->user_id=1; // we default to '1' because we do not have logged in user
$cart_item->product_id=$product_id;
$cart_item->quantity=$quantity;

// check if the item is in the cart, if it is, do not add
if($cart_item->exists()){
	// redirect to product list and tell the user it was added to cart
	header("Location: cart.php?action=exists");
}

// else, add the item to cart
else{
	// add to cart
	if($cart_item->create()){
		// redirect to product list and tell the user it was added to cart
		header("Location: product.php?id={$product_id}&action=added");
	}else{
		header("Location: product.php?id={$product_id}&action=unable_to_add");
	}
}
?>

8.3 Put create() method

The previous section will not work without the following code inside our /objects/cart_item.php file.

// create cart item record
function create(){

    // to get times-tamp for 'created' field
    $this->created=date('Y-m-d H:i:s');

    // query to insert cart item record
    $query = "INSERT INTO
                " . $this->table_name . "
            SET
				product_id = :product_id,
				quantity = :quantity,
				user_id = :user_id,
				created = :created";

	// prepare query statement
    $stmt = $this->conn->prepare($query);

	// sanitize
	$this->product_id=htmlspecialchars(strip_tags($this->product_id));
	$this->quantity=htmlspecialchars(strip_tags($this->quantity));
	$this->user_id=htmlspecialchars(strip_tags($this->user_id));

	// bind values
    $stmt->bindParam(":product_id", $this->product_id);
    $stmt->bindParam(":quantity", $this->quantity);
    $stmt->bindParam(":user_id", $this->user_id);
	$stmt->bindParam(":created", $this->created);

	// execute query
    if($stmt->execute()){
        return true;
    }

    return false;
}

8.4 Create cart.php

Create cart.php with the following basic code.

<?php
// connect to database
include 'config/database.php';

// include objects
include_once "objects/product.php";
include_once "objects/product_image.php";
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$product = new Product($db);
$product_image = new ProductImage($db);
$cart_item = new CartItem($db);

// set page title
$page_title="Cart";

// include page header html
include 'layout_head.php';

// contents will be here 

// layout footer 
include 'layout_foot.php';
?>

8.5 Display message based on action

We'll display message on cart.php based on given action. Put the following code after "include 'layout_head.php';" of the previous section.

$action = isset($_GET['action']) ? $_GET['action'] : "";

echo "<div class='col-md-12'>";
	if($action=='removed'){
		echo "<div class='alert alert-info'>";
			echo "Product was removed from your cart!";
		echo "</div>";
	}

	else if($action=='quantity_updated'){
		echo "<div class='alert alert-info'>";
			echo "Product quantity was updated!";
		echo "</div>";
	}

	else if($action=='exists'){
		echo "<div class='alert alert-info'>";
			echo "Product already exists in your cart!";
		echo "</div>";
	}

	else if($action=='cart_emptied'){
		echo "<div class='alert alert-info'>";
			echo "Cart was emptied.";
		echo "</div>";
	}

	else if($action=='updated'){
		echo "<div class='alert alert-info'>";
			echo "Quantity was updated.";
		echo "</div>";
	}

	else if($action=='unable_to_update'){
		echo "<div class='alert alert-danger'>";
			echo "Unable to update quantity.";
		echo "</div>";
	}
echo "</div>";

8.6 Display cart items

Put the following code based on the code of the previous section.

// $cart_count variable is initialized in navigation.php
if($cart_count>0){

	$cart_item->user_id="1";
	$stmt=$cart_item->read();

	$total=0;
	$item_count=0;

	while ($row = $stmt->fetch(PDO::FETCH_ASSOC)){
        extract($row);

		$sub_total=$price*$quantity;

		echo "<div class='cart-row'>";
			echo "<div class='col-md-8'>";
				// product name
				echo "<div class='product-name m-b-10px'>";
					echo "<h4>{$name}</h4>";
				echo "</div>";

				// update quantity
				echo "<form class='update-quantity-form'>";
					echo "<div class='product-id' style='display:none;'>{$id}</div>";
					echo "<div class='input-group'>";
						echo "<input type='number' name='quantity' value='{$quantity}' class='form-control cart-quantity' min='1' />";
							echo "<span class='input-group-btn'>";
								echo "<button class='btn btn-default update-quantity' type='submit'>Update</button>";
							echo "</span>";
					echo "</div>";
				echo "</form>";

				// delete from cart
				echo "<a href='remove_from_cart.php?id={$id}' class='btn btn-default'>";
					echo "Delete";
				echo "</a>";
			echo "</div>";

			echo "<div class='col-md-4'>";
				echo "<h4>$" . number_format($price, 2, '.', ',') . "</h4>";
			echo "</div>";
		echo "</div>";

		$item_count += $quantity;
		$total+=$sub_total;
	}

	echo "<div class='col-md-8'></div>";
	echo "<div class='col-md-4'>";
		echo "<div class='cart-row'>";
			echo "<h4 class='m-b-10px'>Total ({$item_count} items)</h4>";
			echo "<h4>$" . number_format($total, 2, '.', ',') . "</h4>";
	        echo "<a href='checkout.php' class='btn btn-success m-b-10px'>";
	        	echo "<span class='glyphicon glyphicon-shopping-cart'></span> Proceed to Checkout";
	        echo "</a>";
		echo "</div>";
	echo "</div>";

}

else{
	echo "<div class='col-md-12'>";
		echo "<div class='alert alert-danger'>";
			echo "No products found in your cart!";
		echo "</div>";
	echo "</div>";
}

8.7 Put read() method in cart item object

Open /objects/cart_item.php and add the following code. The previous section will not work without it. This read() method will query the database and return the products added to the cart.

// read items in the cart
public function read(){

	$query="SELECT p.id, p.name, p.price, ci.quantity, ci.quantity * p.price AS subtotal
			FROM " . $this->table_name . " ci
				LEFT JOIN products p
					ON ci.product_id = p.id
			WHERE ci.user_id=:user_id";

	// prepare query statement
	$stmt = $this->conn->prepare($query);

	// sanitize
	$this->user_id=htmlspecialchars(strip_tags($this->user_id));

	// bind value
	$stmt->bindParam(":user_id", $this->user_id, PDO::PARAM_INT);

	// execute query
	$stmt->execute();

	// return values
	return $stmt;
}

8.8 Read products by IDs

The previous section will not work without the following "readByIds()" method inside "objects/product.php" file.

// read all product based on product ids included in the $ids variable
// reference http://stackoverflow.com/a/10722827/827418
public function readByIds($ids){

	$ids_arr = str_repeat('?,', count($ids) - 1) . '?';

	// query to select products
	$query = "SELECT id, name, price FROM " . $this->table_name . " WHERE id IN ({$ids_arr}) ORDER BY name";

	// prepare query statement
	$stmt = $this->conn->prepare($query);

	// execute query
	$stmt->execute($ids);

	// return values from database
	return $stmt;
}

8.9 Output

Output screenshots are coming soon!

9.0 How to update cart?

9.1 Update cart quantity with JavaScript

We have the 'update' button on cart.php file. When that button was clicked, a javascript code is triggered. Put the following code inside "$(document).ready(function(){" of layout_foot.php file.

// update quantity button listener
$('.update-quantity-form').on('submit', function(){

	// get basic information for updating the cart
	var id = $(this).find('.product-id').text();
	var quantity = $(this).find('.cart-quantity').val();

	// redirect to update_quantity.php, with parameter values to process the request
	window.location.href = "update_quantity.php?id=" + id + "&quantity=" + quantity;
	return false;
});

9.2 PHP script to update cart

The previous section will not work without the update_quantity.php file with the following code inside it.

<?php
// get the product id
$product_id = isset($_GET['id']) ? $_GET['id'] : 1;
$quantity = isset($_GET['quantity']) ? $_GET['quantity'] : "";

// make quantity a minimum of 1
$quantity=$quantity<=0 ? 1 : $quantity;

// connect to database
include 'config/database.php';

// include object
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$cart_item = new CartItem($db);

// set cart item values
$cart_item->user_id=1; // we default to '1' because we do not have logged in user
$cart_item->product_id=$product_id;
$cart_item->quantity=$quantity;

// add to cart
if($cart_item->update()){
	// redirect to product list and tell the user it was added to cart
	header("Location: cart.php?action=updated");
}else{
	header("Location: cart.php?action=unable_to_update");
}
?>

9.3 Update cart item in database

The previous section will not work without the following update() method inside /objects/cart_item.php file.

// create cart item record
function update(){

    // query to insert cart item record
    $query = "UPDATE " . $this->table_name . "
            SET quantity=:quantity
            WHERE product_id=:product_id AND user_id=:user_id";

    // prepare query statement
    $stmt = $this->conn->prepare($query);

    // sanitize
    $this->quantity=htmlspecialchars(strip_tags($this->quantity));
    $this->product_id=htmlspecialchars(strip_tags($this->product_id));
    $this->user_id=htmlspecialchars(strip_tags($this->user_id));

    // bind values
    $stmt->bindParam(":quantity", $this->quantity);
    $stmt->bindParam(":product_id", $this->product_id);
    $stmt->bindParam(":user_id", $this->user_id);

    // execute query
    if($stmt->execute()){
        return true;
    }

    return false;
}

9.4 How to remove product from cart?

We have the 'remove' button on cart.php file. When that button was clicked, the remove_from_cart.php file with the following code will be executed.

<?php
// get the product id
$product_id = isset($_GET['id']) ? $_GET['id'] : "";

// connect to database
include 'config/database.php';

// include object
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$cart_item = new CartItem($db);

// remove cart item from database
$cart_item->user_id=1; // we default to '1' because we do not have logged in user
$cart_item->product_id=$product_id;
$cart_item->delete();

// redirect to product list and tell the user it was added to cart
header('Location: cart.php?action=removed&id=' . $id);
?>

9.5 Put delete() method

The previous section will not work without the following method inside our /objects/cart_item.php file.

// remove cart item by user and product
public function delete(){

	// delete query
	$query = "DELETE FROM " . $this->table_name . " WHERE product_id=:product_id AND user_id=:user_id";
	$stmt = $this->conn->prepare($query);

	// sanitize
	$this->product_id=htmlspecialchars(strip_tags($this->product_id));
	$this->user_id=htmlspecialchars(strip_tags($this->user_id));

	// bind ids
	$stmt->bindParam(":product_id", $this->product_id);
	$stmt->bindParam(":user_id", $this->user_id);

	if($stmt->execute()){
		return true;
	}

    return false;
}

9.6 Create the checkout page

The checkout page looks like the cart page but the items cannot be updated or removed. It just like the summary of orders. Create checkout.php with the following code.

<?php
// connect to database
include 'config/database.php';

// include objects
include_once "objects/product.php";
include_once "objects/product_image.php";
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$product = new Product($db);
$product_image = new ProductImage($db);
$cart_item = new CartItem($db);

// set page title
$page_title="Checkout";

// include page header html
include 'layout_head.php';

// $cart_count variable is initialized in navigation.php
if($cart_count>0){

	$cart_item->user_id="1";
	$stmt=$cart_item->read();

	$total=0;
	$item_count=0;

	while ($row = $stmt->fetch(PDO::FETCH_ASSOC)){
        extract($row);

		$sub_total=$price*$quantity;

		echo "<div class='cart-row'>";
			echo "<div class='col-md-8'>";

				echo "<div class='product-name m-b-10px'><h4>{$name}</h4></div>";
                echo $quantity>1 ? "<div>{$quantity} items</div>" : "<div>{$quantity} item</div>";

			echo "</div>";

			echo "<div class='col-md-4'>";
				echo "<h4>$" . number_format($price, 2, '.', ',') . "</h4>";
			echo "</div>";
		echo "</div>";

		$item_count += $quantity;
		$total+=$sub_total;
	}

	echo "<div class='col-md-12 text-align-center'>";
		echo "<div class='cart-row'>";
            if($item_count>1){
    			echo "<h4 class='m-b-10px'>Total ({$item_count} items)</h4>";
            }else{
                echo "<h4 class='m-b-10px'>Total ({$item_count} item)</h4>";
            }
			echo "<h4>$" . number_format($total, 2, '.', ',') . "</h4>";

	        echo "<a href='place_order.php' class='btn btn-lg btn-success m-b-10px'>";
	        	echo "<span class='glyphicon glyphicon-shopping-cart'></span> Place Order";
	        echo "</a>";
		echo "</div>";
	echo "</div>";

}

else{
	echo "<div class='col-md-12'>";
		echo "<div class='alert alert-danger'>";
			echo "No products found in your cart!";
		echo "</div>";
	echo "</div>";
}

include 'layout_foot.php';
?>

9.7 Create place_order.php

We'll use this file to show a "thank you" message and remove all items in the cart.

<?php
// include classes
include_once "config/database.php";
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$cart_item = new CartItem($db);

// remove all cart item by user, from database
$cart_item->user_id=1; // we default to '1' because we do not have logged in user
$cart_item->deleteByUser();

// set page title
$page_title="Thank You!";

// include page header HTML
include_once 'layout_head.php';

echo "<div class='col-md-12'>";
	// tell the user order has been placed
	echo "<div class='alert alert-success'>";
		echo "<strong>Your order has been placed!</strong> Thank you very much!";
	echo "</div>";
echo "</div>";

// include page footer HTML
include_once 'layout_foot.php';

9.8 Delete all items in the cart

The previous section will not work without the following method. Open /objects/cart_item.php and put it inside.

// remove cart items by user
public function deleteByUser(){
    // delete query
    $query = "DELETE FROM " . $this->table_name . " WHERE user_id=:user_id";
	$stmt = $this->conn->prepare($query);

	// sanitize
    $this->user_id=htmlspecialchars(strip_tags($this->user_id));

    // bind id
    $stmt->bindParam(":user_id", $this->user_id);

	if($stmt->execute()){
		return true;
	}

    return false;
}

9.9 Output

Output screenshots are coming soon!

10.0 How to make the product page?

10.1 Create product.php

Create product.php with the following basic code.

<?php
// include classes
include_once "config/database.php";
include_once "objects/product.php";
include_once "objects/product_image.php";
include_once "objects/cart_item.php";

// get database connection
$database = new Database();
$db = $database->getConnection();

// initialize objects
$product = new Product($db);
$product_image = new ProductImage($db);
$cart_item = new CartItem($db);

// get ID of the product to be edited
$id = isset($_GET['id']) ? $_GET['id'] : die('ERROR: missing ID.');
$action = isset($_GET['action']) ? $_GET['action'] : "";

// set the id as product id property
$product->id = $id;

// to read single record product
$product->readOne();

// set page title
$page_title = $product->name;

// include page header HTML
include_once 'layout_head.php';

// content will be here

// include page footer HTML
include_once 'layout_foot.php';
?>

10.2 Read product details

Put the following code after "$product_image = new ProductImage($db);" code of the previous section.

// get ID of the product to be edited and action
$id = isset($_GET['id']) ? $_GET['id'] : die('ERROR: missing ID.');
$action = isset($_GET['action']) ? $_GET['action'] : "";

// set the id as product id property
$product->id = $id;

// to read single record product
$product->readOne();

// set page title
$page_title = $product->name;

10.3 Read one product method

The previous section will not work without the "readOne()" method. Add the following method inside "objects/product.php" file.

// used when filling up the update product form
function readOne(){

	// query to select single record
	$query = "SELECT
				name, description, price
			FROM
				" . $this->table_name . "
			WHERE
				id = ?
			LIMIT
				0,1";

	// prepare query statement
	$stmt = $this->conn->prepare( $query );

	// sanitize
	$this->id=htmlspecialchars(strip_tags($this->id));

	// bind product id value
	$stmt->bindParam(1, $this->id);

	// execute query
	$stmt->execute();

	// get row values
	$row = $stmt->fetch(PDO::FETCH_ASSOC);

	// assign retrieved row value to object properties
	$this->name = $row['name'];
	$this->description = $row['description'];
	$this->price = $row['price'];
}

10.4 Display message based on action

Open product.php file. Put the following code after ,span class="coan_code">include_once 'layout_head.php'; code.

echo "<div class='col-md-12'>";
	if($action=='added'){
		echo "<div class='alert alert-info'>";
			echo "Product was added to your cart!";
		echo "</div>";
	}

	else if($action=='unable_to_add'){
		echo "<div class='alert alert-info'>";
			echo "Unable to add product to cart. Please contact Admin.";
		echo "</div>";
	}
echo "</div>";

// product thumbnail will be here

10.5 Display product thumbnails

When these product thumbnails were hovered, it displayes a larger version of the image. It is Amazon-style.

Open product.php file and replace // product thumbnail will be here comment with the following code.

// set product id
$product_image->product_id=$id;

// read all related product image
$stmt_product_image = $product_image->readByProductId();

// count all relatd product image
$num_product_image = $stmt_product_image->rowCount();

echo "<div class='col-md-1'>";
	// if count is more than zero
	if($num_product_image>0){
		// loop through all product images
		while ($row = $stmt_product_image->fetch(PDO::FETCH_ASSOC)){
			// image name and source url
			$product_image_name = $row['name'];
			$source="uploads/images/{$product_image_name}";
			echo "<img src='{$source}' class='product-img-thumb' data-img-id='{$row['id']}' />";
		}
	}else{ echo "No images."; }
echo "</div>";

10.6 Read images related to product

The previous section section will not work without the "readByProductId()" method inside "objects/product_image.php" file.

// read all product image related to a product
function readByProductId(){

	// select query
	$query = "SELECT id, product_id, name
			FROM " . $this->table_name . "
			WHERE product_id = ?
			ORDER BY name ASC";

	// prepare query statement
	$stmt = $this->conn->prepare( $query );

	// sanitize
	$this->product_id=htmlspecialchars(strip_tags($this->product_id));

	// bind prodcut id variable
	$stmt->bindParam(1, $this->product_id);

	// execute query
	$stmt->execute();

	// return values
	return $stmt;
}

10.7 Display product image

Only one product image are displayed at a time. This part displays the larger product image based on the hovered product thumbnail. Put the following code after the previous section's code.

echo "<div class='col-md-4' id='product-img'>";

	// read all related product image
	$stmt_product_image = $product_image->readByProductId();
	$num_product_image = $stmt_product_image->rowCount();

	// if count is more than zero
	if($num_product_image>0){
		// loop through all product images
		$x=0;
		while ($row = $stmt_product_image->fetch(PDO::FETCH_ASSOC)){
			// image name and source url
			$product_image_name = $row['name'];
			$source="uploads/images/{$product_image_name}";
			$show_product_img=$x==0 ? "display-block" : "display-none";
			echo "<a href='{$source}' target='_blank' id='product-img-{$row['id']}' class='product-img {$show_product_img}'>";
				echo "<img src='{$source}' style='width:100%;' />";
			echo "</a>";
			$x++;
		}
	}else{ echo "No images."; }
echo "</div>";

10.8 Make image hover work

Put the following jQuery code inside "$(document).ready(function(){" of layout_foot.php file.

// change product image on hover
$(document).on('mouseenter', '.product-img-thumb', function(){
	var data_img_id = $(this).attr('data-img-id');
	$('.product-img').hide();
	$('#product-img-'+data_img_id).show();
});

10.9 Display product details

This part display product price, description and category. Put the following code after the previous section's code.

echo "<div class='col-md-5'>";

	echo "<div class='product-detail'>Price:</div>";
	echo "<h4 class='m-b-10px price-description'>$" . number_format($product->price, 2, '.', ',') . "</h4>";

	echo "<div class='product-detail'>Product description:</div>";
	echo "<div class='m-b-10px'>";
		// make html
		$page_description = htmlspecialchars_decode(htmlspecialchars_decode($product->description));

		// show to user
		echo $page_description;
	echo "</div>";

	echo "<div class='product-detail'>Product category:</div>";
	echo "<div class='m-b-10px'>{$product->category_name}</div>";

echo "</div>";

10.10 Render 'Cart' button

Now we will display 'Add to cart' button if the product is not yet added to cart. Else, we will display 'update cart' button.

Place the following code after the previous section's code.

echo "<div class='col-md-2'>";
	// cart item settings
	$cart_item->user_id=1; // we default to a user with ID "1" for now
	$cart_item->product_id=$id;

	// if product was already added in the cart
	if($cart_item->exists()){
		echo "<div class='m-b-10px'>This product is already in your cart.</div>";
		echo "<a href='cart.php' class='btn btn-success w-100-pct'>";
			echo "Update Cart";
		echo "</a>";
	}

	// if product was not added to the cart yet
	else{

		echo "<form class='add-to-cart-form'>";
			// product id
			echo "<div class='product-id display-none'>{$id}</div>";

			// select quantity
			echo "<div class='m-b-10px f-w-b'>Quantity:</div>";
			echo "<input type='number' class='form-control m-b-10px cart-quantity' value='1' min='1' />";

			// enable add to cart button
			echo "<button style='width:100%;' type='submit' class='btn btn-primary add-to-cart m-b-10px'>";
				echo "<span class='glyphicon glyphicon-shopping-cart'></span> Add to cart";
			echo "</button>";

		echo "</form>";
	}
echo "</div>";

10.11 Output

Output screenshots are coming soon!

11.0 What People Say About This Code?

I'm so glad that this code delights other people. The following are some of them from the comments section!

★★★★★ "Hey Mike, my name is Leonardo from Argentina. I've been reading your blog since like 4 months from now, and I really must say: your tutorials are very good, they has helped me in many of my works... Well, thank you very much man. I really admire your work." ~ Leonardo

★★★★★ "Man, your tut's are awesome. Im so glad ive found your blog. Big respect!" ~ Milos

★★★★★ "I bought your level-2 source code and it was so good, very big help for me. It was worth it. Thank you very much!" ~ Ashley Deanna Plata

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12.0 Download the LEVEL 1 Source Code

You can get the source code by following the whole, well detailed and free tutorial above. But isn’t it more convenient if you can just download the complete source code we used, and play around it?

There’s a small fee in getting the complete source code, it is small compared to the:

✔ Value or skill upgrade it can bring you, or	YES
✔ Income you can get from your website project or business.	YES
✔ Precious time you save.	YES
✔ Expert advice and support (if you have any questions related to the source code)	YES

For a limited time, I will give you the source code for a low price. DOWNLOAD THE SOURCE CODE LEVEL you desire by clicking its the BUY button below.

The LEVEL 1 Source code has the following features:

13.0 Download the LEVEL 2 Source Code

Download the LEVEL 2 Source code, it has more features such as:

14.0 Download the PHP Shopping Cart Module

It has several features you will enjoy learning. Some examples: how to handle the users, shopping cart and ordering using the PHP & MySQL technology. Click here to learn more or download it now using the button below.

•  LEVEL 1 Source Code – $19.99
•  LEVEL 2 Source Code – $29.99
•  LEVEL 3 Source Code – $49.99

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15.0 Download the "PHP Shopping Cart SYSTEM" Source Code

Many of you requested this source code. You needed a shopping cart system with user management (merchant and customer), product management, category management, order management, security and more features based on our source codes here in codeofaninja.com. Click here to learn more.

16.0 What's Next?

We made another version of this tutorial. We used PHP session variables to store cart data. This is a great tutorial about PHP sessions.

You can find the tutorial here: PHP and MySQL Shopping Cart Tutorial – Using SESSIONS To Store Cart Data

17.0 Related Tutorials

18.0 Notes

Thank you for studying our tutorial about simple PHP MySQL shopping cart tutorial!