How to use PHP to develop online shopping cart functionality

How to use PHP to develop online shopping cart function

In modern society, online shopping has become an indispensable part of people's lives. The shopping cart function is a very important part of an online mall. The shopping cart allows users to temporarily save items and make modifications and settlement at any time. In this article, we will introduce how to use PHP to develop a simple and fully functional online shopping cart function.

1. Create database table
   First, create a database table named "cart", which is used to store product information in the shopping cart. The table structure can be as follows:

CREATE TABLE cart (
    id INT PRIMARY KEY AUTO_INCREMENT,
    product_id INT NOT NULL,
    user_id INT NOT NULL,
    quantity INT DEFAULT 1,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

2. Configuring database connection
   In PHP code, database connection information needs to be configured. Create a file named "config.php" and add the following code:

<?php

$dbHost = "localhost";
$dbUser = "your_username";
$dbPass = "your_password";
$dbName = "your_database";

$conn = mysqli_connect($dbHost, $dbUser, $dbPass, $dbName);

if (!$conn) {
    die("数据库连接失败: " . mysqli_connect_error());
}

Please replace "your_username", "your_password", and "your_database" with your actual database username and password and database name.

3. Add items to the shopping cart
   Create a file named "addToCart.php" to handle the user's request to add items to the shopping cart. The following is a sample code:

<?php

session_start(); // 开启会话

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $productId = $_POST["product_id"];
    $userId = $_SESSION["user_id"];

    $query = "INSERT INTO cart (product_id, user_id) VALUES ('$productId', '$userId')";
    mysqli_query($conn, $query);
}

This code obtains the product ID through a POST request, and inserts the product ID and the current user's ID into the "cart" table.

4. Display shopping cart contents
   Create a file named "viewCart.php" to display product information in the shopping cart. The following is a sample code:

<?php

session_start(); // 开启会话

$userId = $_SESSION["user_id"];
$query = "SELECT c.*, p.name, p.price FROM cart c LEFT JOIN products p ON c.product_id = p.id WHERE c.user_id = '$userId'";
$result = mysqli_query($conn, $query);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        echo "产品名称: " . $row["name"] . "<br>";
        echo "价格: " . $row["price"] . "<br>";
        echo "数量: " . $row["quantity"] . "<br>";
        echo "<hr>";
    }
} else {
    echo "购物车为空";
}

This code queries the product information in the shopping cart through a left join (LEFT JOIN) and outputs the name, price and quantity of each product.

5. Update the quantity of items in the shopping cart
   Create a file named "updateQuantity.php" to update the quantity of items in the shopping cart. The following is a sample code:

<?php

session_start(); // 开启会话

if ($_SERVER["REQUEST_METHOD"] == "POST") {
    $cartId = $_POST["cart_id"];
    $quantity = $_POST["quantity"];

    $query = "UPDATE cart SET quantity = '$quantity' WHERE id = '$cartId'";
    mysqli_query($conn, $query);
}

This code obtains the ID and quantity of the shopping cart item through a POST request, and updates the quantity field of the corresponding item in the "cart" table.

Through the above steps, you have successfully developed a simple online shopping cart function. Users can add items to the shopping cart, view the items in the shopping cart, and update the quantity of items in the shopping cart. Of course, you can extend and beautify the functions according to actual needs.

I hope this article can help you understand how to use PHP to develop online shopping cart functions. I wish you happy programming and build a more complete mall shopping experience!

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