问注册表到mysql数据库

EN

<?php

// setup PDO database connection
$servername = 'localhost';
$username = 'root';
$password = 'password';

try {
    $conn = new PDO("mysql:host=$servername;dbname=myDB", $username, $password);
    // set the PDO error mode to exception
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo 'Connected successfully';
}
catch(PDOException $e)
{
    echo 'Connection failed: ' . $e->getMessage();
}

?>

<?php include './database.php'; ?>

<p>
<!-- remove action to run same page -->
<form method="POST">
    <br>
    <!-- set email if page is reloading with error; use htmlspecialchars to encode XSS-relevant characters-->
    Email:<input type="text" name="email" value="<?php echo isset($_POST['email']) ? htmlspecialchars($_POST['email']) : null; ?>">
    <br>
    Password:<input type="password" name="password">
    <br>
    Confirm Password:<input type="password" name="confirmpass">
    <br>
    <input type="submit" value="Sign up">
</form>
</p>
<p>
    <?php
    // run on same page to get error message
    if(isset($_POST)) {
        echo register();
    } ?>
</p>


<?php

/**
 * register function
 * redirect if register is successful
 * @return null|string
 */
function register(): ?string {
    $error = null;

    // null coalescing operator
    // replaces
    /*if(isset($_POST['email'])) {
        $email = $_POST['email'];
    } else {
        $email = null;
    }*/
    $email = $_POST['email'] ?? null;
    $password = $_POST['password'] ?? null;
    $confirmPass = $_POST['confirmpass'] ?? null;

    // check if fields are empty
    if ($email !== null && $password !== null && $confirmPass !== null) {

        // non looping do-while-loop to exit/break on error
        // prevent nested ifs
        do {
            // remove unallowed characters from email address
            $email = filter_var($email, FILTER_SANITIZE_EMAIL);

            // check if email address has valid format
            if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
                $error = 'Please enter a valid email address';
                break;
            }

            // check if both passwords match
            if ($password !== $confirmPass) {
                $error = 'Passwords do not match';
                break;
            }

            // check if user already exists
            $stmt = $conn->prepare('SELECT COUNT(*) FROM database11 WHERE email = :email');
            // bind value of $email to placeholder :email
            $stmt->bindParam(':email', $email);

            // execute the query and fetch the first column with count-result
            if ($stmt->execute() && $stmt->fetchColumn() > 0) {
                $error = 'Email is already registered.';
                break;
            }


            // hash password for database
            $hashedPassword = password_hash($password, PASSWORD_DEFAULT);

            // insert new user
            $stmt = $conn->prepare('INSERT INTO database11 (email, password) VALUES (:email, :password)');
            $stmt->bindValue(':email', $email);
            $stmt->bindValue(':password', $hashedPassword);

            if ($stmt->execute()) {
                // redirect to success page
                header('Location: ./success.php');
                // stop current request
                exit();
            }

            $error = 'Could not register';

        } while (0);

    } else {
        $error = 'Some fields are empty';
    }

    return $error;
}