如何在PHP中使用邮件验证来增强登录注册的安全性？

CREATE TABLE `users` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `email` varchar(255) NOT NULL,
  `password` varchar(255) NOT NULL,
  `status` tinyint(1) NOT NULL DEFAULT '0',
  `verification_code` varchar(255) NOT NULL,
  PRIMARY KEY (`id`)
);

<?php
// 生成随机验证码
$verificationCode = uniqid();

// 将邮箱、密码、验证码等信息保存到数据库
$query = "INSERT INTO users (email, password, verification_code) VALUES ('$email', '$password', '$verificationCode')";
// 执行查询操作
$result = mysqli_query($conn, $query);

// 发送验证邮件
$to = $email;
$subject = "账号激活邮件";
$message = "请点击以下链接激活您的账号：

";
$message .= "http://example.com/activate.php?code=".$verificationCode;
$headers = "From: no-reply@example.com";
mail($to, $subject, $message, $headers);
?>

<?php
if(isset($_GET['code'])) {
  // 获取URL中的验证码
  $verificationCode = $_GET['code'];

  // 验证验证码
  $query = "SELECT * FROM users WHERE verification_code = '$verificationCode'";
  // 执行查询操作
  $result = mysqli_query($conn, $query);

  if(mysqli_num_rows($result) > 0) {
    // 更新用户状态为已激活
    $query = "UPDATE users SET status = 1 WHERE verification_code = '$verificationCode'";
    // 执行更新操作
    mysqli_query($conn, $query);
    echo "账号已激活，您可以登录了！";
  } else {
    echo "无效的验证码！";
  }
}
?>