CREATE TABLE IF NOT EXISTS `demo_visits` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `cert` VARCHAR(20) NOT NULL,
  `visited_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `ip_address` VARCHAR(45) DEFAULT NULL,
  `user_agent` TEXT DEFAULT NULL,
  `referrer` TEXT DEFAULT NULL,
  INDEX `idx_cert` (`cert`),
  INDEX `idx_visited_at` (`visited_at`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;