如何使用PHP开发在线商城购物车功能

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
);

<?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());
}

<?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);
}

<?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";
}

<?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);
}