prepare('SELECT id, password, role FROM users WHERE username = ?'); $stmt->execute([$username]); $user = $stmt->fetch(); if ($user && password_verify($password, $user['password'])) { $_SESSION['user_id'] = $user['id']; $_SESSION['role'] = $user['role']; header('Location: index.php'); exit; } else { $error = 'Invalid username or password.'; } } } ?>