CREATE TABLE IF NOT EXISTS `kb_documents` (
  `id` INT AUTO_INCREMENT PRIMARY KEY,
  `title` VARCHAR(255) NOT NULL,
  `content` TEXT NOT NULL,
  `tags` VARCHAR(255),
  `product_id` INT,
  `language` VARCHAR(10) NOT NULL DEFAULT 'en',
  `is_active` BOOLEAN NOT NULL DEFAULT TRUE,
  `created_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  `updated_at` TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  FOREIGN KEY (`product_id`) REFERENCES `products`(`id`) ON DELETE SET NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;