如何利用PHP实现商城的礼品卡系统

for ($i = 1; $i <= 10; $i++) {
  $giftCardNo = mt_rand(100000, 999999); // 生成6位随机数作为礼品卡编号
  $giftCardValue = 100; // 默认面值为100元
  $giftCardStatus = 0; // 默认状态为未使用
  $sql = "INSERT INTO gift_card (no, value, status) VALUES ('$giftCardNo', '$giftCardValue', '$giftCardStatus')";
  mysqli_query($conn, $sql);
}

$giftCardNo = mt_rand(100000, 999999); // 生成6位随机数作为礼品卡编号
$giftCardValue = $_POST['value']; // 获取用户输入的礼品卡面值
$giftCardStatus = 0; // 默认状态为未使用
$sql = "INSERT INTO gift_card (no, value, status) VALUES ('$giftCardNo', '$giftCardValue', '$giftCardStatus')";
mysqli_query($conn, $sql);
$to = $_POST['email']; // 收件人邮箱
$subject = "您收到一张礼品卡"; // 邮件标题
$message = "您好，您收到一张价值 $giftCardValue 元的礼品卡，编号为 $giftCardNo，请在使用时输入编号和密码进行验证。"; // 邮件内容
$headers = "From: webmaster@example.com"; // 发件人
mail($to, $subject, $message, $headers); // 发送邮件

$giftCardNo = $_POST['no']; // 获取用户输入的礼品卡编号
$giftCardPwd = $_POST['pwd']; // 获取用户输入的礼品卡密码
$sql = "SELECT * FROM gift_card WHERE no='$giftCardNo' AND pwd='$giftCardPwd' AND status=0"; // 查询礼品卡表
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
  $row = mysqli_fetch_assoc($result);
  $giftCardValue = $row['value']; // 获取礼品卡面值
  $giftCardStatus = 1; // 修改礼品卡状态为已使用
  $sql = "UPDATE gift_card SET status='$giftCardStatus' WHERE no='$giftCardNo'";
  mysqli_query($conn, $sql);
  $discount = $giftCardValue; // 根据礼品卡面值计算优惠金额
} else {
  $discount = 0; // 如果礼品卡无效，则不享受任何优惠
}