CREATE TABLE IF NOT EXISTS `chat_sessions` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `user_id` INT,
  `client_id` INT,
  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  FOREIGN KEY (`user_id`) REFERENCES `users`(`id`) ON DELETE CASCADE,
  FOREIGN KEY (`client_id`) REFERENCES `clients`(`id`) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;