如何使用PHP数据库连接实现用户订阅功能

<?php
$servername = "localhost";
$username = "your_username";
$password = "your_password";
$dbname = "your_database_name";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Connected successfully";
} catch (PDOException $e) {
    echo "Connection failed: " . $e->getMessage();
}
?>

<?php
function subscribe($email, $subscriptionType) {
    // 输入验证
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        return "请输入有效的电子邮件地址";
    }

    // 将订阅信息插入到数据库中
    try {
        $stmt = $conn->prepare("INSERT INTO subscriptions (email, subscription_type, subscription_date) VALUES (?, ?, NOW())");
        $stmt->execute([$email, $subscriptionType]);
        return "订阅成功";
    } catch (PDOException $e) {
        return "订阅失败：" . $e->getMessage();
    }
}
?>

<?php
function unsubscribe($subscriptionId) {
    try {
        $stmt = $conn->prepare("DELETE FROM subscriptions WHERE id = ?");
        $stmt->execute([$subscriptionId]);
        return "取消订阅成功";
    } catch (PDOException $e) {
        return "取消订阅失败：" . $e->getMessage();
    }
}
?>