How to implement a simple shopping cart function using PHP

How to use PHP to implement a simple shopping cart function

The shopping cart function is an essential part of an e-commerce website, which allows users to place items they are interested in Add to cart, then proceed to checkout or continue browsing and adding items. This article will introduce how to use PHP to implement a simple shopping cart function and provide specific code examples.

1. Create database and tables

First, we need to create a database and a table for storing shopping cart data.

CREATE DATABASE shopping_cart;
USE shopping_cart;

CREATE TABLE cart(
    id INT AUTO_INCREMENT PRIMARY KEY,
    product_name VARCHAR(50),
    price DECIMAL(10,2),
    quantity INT,
    total DECIMAL(10,2)
);

2. Create a product list page

Next, we need to create a product list page where users can select products to add to their shopping cart. The following is a simple sample code:

<?php
// 连接数据库
$connection = mysqli_connect("localhost", "username", "password", "shopping_cart");

// 查询所有商品
$query = "SELECT * FROM products";
$result = mysqli_query($connection, $query);

// 遍历商品并显示在页面上
while($row = mysqli_fetch_assoc($result)) {
    echo "<h3>".$row['product_name']."</h3>";
    echo "<p>价格：".$row['price']."</p>";
    echo "<button onclick='addToCart(".$row['id'].")'>添加到购物车</button>";
}

// 关闭数据库连接
mysqli_close($connection);
?>

<script>
function addToCart(productId) {
    // 向后端发送请求，将商品添加到购物车
    var xhr = new XMLHttpRequest();
    xhr.open("POST", "add_to_cart.php", true);
    xhr.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
    xhr.onreadystatechange = function() {
        if (xhr.readyState === 4 && xhr.status === 200) {
            alert("商品已添加到购物车！");
        }
    };
    xhr.send("productId=" + productId);
}
</script>

3. Create the backend code for adding items to the shopping cart

In the previous step, we called a function called ## The back-end script of #add_to_cart.php is used to add selected items to the shopping cart. Here is the sample code for the script:

<?php
// 获取待添加到购物车的商品ID
$productId = $_POST['productId'];

// 根据商品ID查询商品信息
$connection = mysqli_connect("localhost", "username", "password", "shopping_cart");
$query = "SELECT * FROM products WHERE id = '".$productId."'";
$result = mysqli_query($connection, $query);
$product = mysqli_fetch_assoc($result);

// 添加商品到购物车表格中
$insertQuery = "INSERT INTO cart (product_name, price, quantity, total) 
                VALUES ('".$product['product_name']."', '".$product['price']."', 1, '".$product['price']."')";
mysqli_query($connection, $insertQuery);

// 关闭数据库连接
mysqli_close($connection);
?>

Create a shopping cart page

Finally, we need to create a shopping cart page that displays the items the user has added to the shopping cart and calculate the total amount. The following is an example of a simple shopping cart page:

<?php
$connection = mysqli_connect("localhost", "username", "password", "shopping_cart");

$query = "SELECT * FROM cart";
$result = mysqli_query($connection, $query);

$totalPrice = 0;

while($row = mysqli_fetch_assoc($result)) {
    echo "<h3>".$row['product_name']."</h3>";
    echo "<p>价格：".$row['price']."</p>";
    echo "<p>数量：".$row['quantity']."</p>";
    echo "<hr>";
    // 计算总金额
    $totalPrice += $row['total'];
}

echo "<h4>总金额：".$totalPrice."</h4>";

mysqli_close($connection);
?>

So far, we have successfully implemented a simple shopping cart function. Users can select products on the product list page and add them to the shopping cart, and then view the added products and calculate the total amount on the shopping cart page.

It should be noted that this article only provides a basic implementation example. In actual applications, it may be necessary to handle more complex functions such as increasing or decreasing the number of products, deleting products, and user login. Additionally, proper data validation and optimization are required to ensure security and performance.

I hope this article can be helpful to beginners and provide you with some ideas and references in practical applications.

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