二手回收网站利用PHP开发的购物车实时更新功能

CREATE TABLE shopping_cart (
    id INT PRIMARY KEY AUTO_INCREMENT,
    user_id INT,
    product_id INT,
    product_name VARCHAR(255),
    quantity INT,
    price DECIMAL(10, 2)
);

<?php
// 获取商品信息
$product_id = $_POST['product_id'];
$product_name = $_POST['product_name'];
$price = $_POST['price'];

// 获取用户信息（这里假设用户已登录）
$user_id = $_SESSION['user_id'];

// 检查购物车中是否已经存在相同的商品
$query = "SELECT * FROM shopping_cart WHERE user_id = $user_id AND product_id = $product_id";
$result = mysqli_query($connection, $query);

if (mysqli_num_rows($result) > 0) {
    // 如果已存在，则更新商品数量
    $row = mysqli_fetch_assoc($result);
    $quantity = $row['quantity'] + 1;

    $update_query = "UPDATE shopping_cart SET quantity = $quantity WHERE user_id = $user_id AND product_id = $product_id";
    mysqli_query($connection, $update_query);

} else {
    // 如果不存在，则添加新的商品到购物车
    $insert_query = "INSERT INTO shopping_cart (user_id, product_id, product_name, quantity, price) VALUES ($user_id, $product_id, '$product_name', 1, $price)";
    mysqli_query($connection, $insert_query);
}

// 返回购物车页面
header('Location: shopping_cart.php');
?>

// 监听数量输入框的变化
$('.quantity-input').change(function() {
    var product_id = $(this).data('product-id');
    var new_quantity = $(this).val();

    // 向服务器发送Ajax请求，更新购物车中商品的数量
    $.ajax({
        url: 'update_quantity.php',
        type: 'POST',
        data: {
            product_id: product_id,
            new_quantity: new_quantity
        },
        success: function(response) {
            // 更新购物车显示
            $('.product-quantity[data-product-id="' + product_id + '"]').text(new_quantity);
            calculateTotalPrice();
        }
    });
});

// 计算总价
function calculateTotalPrice() {
    var total_price = 0;
    $('.product-row').each(function() {
        var price = $(this).find('.product-price').text();
        var quantity = $(this).find('.product-quantity').text();
        total_price += parseFloat(price) * parseInt(quantity);
    });

    $('.total-price').text(total_price);
}

<?php
// 获取商品和新数量
$product_id = $_POST['product_id'];
$new_quantity = $_POST['new_quantity'];

// 获取用户ID（这里假设用户已登录）
$user_id = $_SESSION['user_id'];

// 更新购物车中商品的数量
$update_query = "UPDATE shopping_cart SET quantity = $new_quantity WHERE user_id = $user_id AND product_id = $product_id";
mysqli_query($connection, $update_query);
?>