// 登録処理
$sql = "insert into users
    (name, email, password, create, modified)
    values
    (:name, :email, :password, now(), now())";
    $stmt = $dbh->prepare($sql);
    $params = array(
        ":name" => $name,
        ":email" => $email,
        ":password" => getSha1Password($password)  // パスワードは暗号化して保存する(関数作成)
    );
    $stmt->execute($params);
    header('Location: '.SITE_URL.'login.php');
    exit;

function getSha1Password($s) {
    return (sha1(PASSWORD_KEY.$s));
}