exec(" CREATE TABLE IF NOT EXISTS `users` ( `id` INT UNSIGNED AUTO_INCREMENT PRIMARY KEY, `fullname` VARCHAR(100) NOT NULL, `username` VARCHAR(50) NOT NULL UNIQUE, `email` VARCHAR(120) NOT NULL UNIQUE, `password_hash` VARCHAR(255) NOT NULL, `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci ");