PHPが開発した中古リサイクルサイトに口座残高キャッシュバック機能を提供

CREATE TABLE users (
    id INT(11) AUTO_INCREMENT PRIMARY KEY,
    username VARCHAR(50) NOT NULL,
    balance DECIMAL(10,2) NOT NULL DEFAULT 0.00
);

<?php
session_start(); // 启动会话

// 检查用户是否已登录
if (!isset($_SESSION['username'])) {
    header("Location: login.php");
    exit;
}

// 获取当前用户的用户名
$username = $_SESSION['username'];

// 连接到数据库
$servername = "localhost";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名称";

$conn = new mysqli($servername, $username, $password, $dbname);

// 检查数据库连接是否成功
if ($conn->connect_error) {
    die("数据库连接失败：" . $conn->connect_error);
}

// 查询当前用户的账户余额
$sql = "SELECT balance FROM users WHERE username = '$username'";
$result = $conn->query($sql);

// 检查查询结果
if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    $balance = $row['balance'];
    echo "您的账户余额：" . $balance;
} else {
    echo "未找到用户信息";
}

// 关闭数据库连接
$conn->close();
?>

<?php
session_start(); // 启动会话

// 检查用户是否已登录
if (!isset($_SESSION['username'])) {
    header("Location: login.php");
    exit;
}

// 获取当前用户的用户名和返现金额
$username = $_SESSION['username'];
$cashbackAmount = $_POST['cashbackAmount'];

// 连接到数据库
$servername = "localhost";
$username = "数据库用户名";
$password = "数据库密码";
$dbname = "数据库名称";

$conn = new mysqli($servername, $username, $password, $dbname);

// 检查数据库连接是否成功
if ($conn->connect_error) {
    die("数据库连接失败：" . $conn->connect_error);
}

// 更新当前用户的账户余额
$sql = "UPDATE users SET balance = balance + $cashbackAmount WHERE username = '$username'";
if ($conn->query($sql) === TRUE) {
    echo "账户余额返现成功";
} else {
    echo "账户余额返现失败：" . $conn->error;
}

// 关闭数据库连接
$conn->close();
?>