CREATE TABLE IF NOT EXISTS `courses` (
    `id` INT AUTO_INCREMENT PRIMARY KEY,
    `title` VARCHAR(255) NOT NULL,
    `description` TEXT NOT NULL,
    `instructor_id` INT,
    `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    FOREIGN KEY (`instructor_id`) REFERENCES `users`(`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;