An example explains how to use php to implement a product shopping cart adding function

With the popularity of online shopping, the function of product shopping cart has also become an indispensable part of shopping websites. In order to facilitate the user's shopping process, the website needs to provide users with a shopping cart system so that users can easily add and manage the items in their shopping carts. This article will introduce how to use PHP to implement a simple product shopping cart adding function.

1. Create database and table

First you need to create a database and corresponding table to store the user's shopping cart data. In MySQL, you can use the following code to create a database named "shoppingcart" and a table named "cart_items".

CREATE DATABASE shoppingcart;
USE shoppingcart;

CREATE TABLE cart_items (
  id INT NOT NULL,                // 购物车ID
  userid INT NOT NULL,            // 用户ID
  productid INT NOT NULL,         // 商品ID
  quantity INT NOT NULL,          // 商品数量
  PRIMARY KEY (id)
);

2. Connecting to the database

Connecting to the database is the first step to access the database using PHP. In order to connect to the MySQL database, you need to use the mysqli_connect() function. This function requires the database hostname, username, password, and the name of the database to connect to.

$host = "localhost";
$user = "root";
$pass = "password";
$dbname = "shoppingcart";

$conn = mysqli_connect($host, $user, $pass, $dbname);

3. Add items to shopping cart

Once you successfully connect to the database, you can start adding items to the shopping cart. The following is a simple PHP script to add items to the shopping cart. This script needs to get the item ID and quantity from the front end and insert this data into the "cart_items" table.

<?php
  $userid = 1;                       // 固定用户ID为1
  $productid = $_POST[&#39;productid&#39;];  // 获取商品ID
  $quantity = $_POST[&#39;quantity&#39;];    // 获取商品数量

  $sql = "INSERT INTO cart_items (userid, productid, quantity) VALUES (?, ?, ?)";
  $stmt = mysqli_prepare($conn, $sql);

  mysqli_stmt_bind_param($stmt, &#39;iii&#39;, $userid, $productid, $quantity);
  mysqli_stmt_execute($stmt);

  mysqli_close($conn);
?>

4. Display shopping cart contents

The last step is to display the shopping cart contents. In the shopping cart page of the website, users can see the list of items in their shopping cart. The following is a simple PHP script that is used to obtain all the items in the user's shopping cart from the "cart_items" table and display them on the front end.

<?php
  $userid = 1;   // 固定用户ID为1

  $sql = "SELECT * FROM cart_items WHERE userid = $userid";
  $result = mysqli_query($conn, $sql);

  while($row = mysqli_fetch_assoc($result)) {
    echo "<p>Product: " . $row['productid'] . ", Quantity: " . $row['quantity'] . "</p>";
  }

  mysqli_close($conn);
?>

The above is a simple method to use PHP to implement the product shopping cart adding function. In practical applications, some security and performance optimizations are also required. For example, user input can be securely filtered to prevent SQL injection attacks; in addition, because there is usually a large amount of product data in the shopping cart, it is necessary to consider paging and caching the shopping cart data to improve the performance of the shopping cart.

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