php mysql生成随机卡号

<?php
function generateRandomCardNumber($length = 16) {
    $characters = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

$cardNumber = generateRandomCardNumber();
echo "Generated Card Number: " . $cardNumber;
?>

CREATE TABLE cards (
    id INT AUTO_INCREMENT PRIMARY KEY,
    card_number VARCHAR(255) NOT NULL UNIQUE,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database_name";

// 创建连接
$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

$cardNumber = generateRandomCardNumber();

$sql = "INSERT INTO cards (card_number) VALUES ('$cardNumber')";

if ($conn->query($sql) === TRUE) {
    echo "New record created successfully";
} else {
    echo "Error: " . $sql . "<br>" . $conn->error;
}

$conn->close();
?>