CREATE TABLE IF NOT EXISTS drive_item_metadata (
  id BIGINT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
  item_id BIGINT UNSIGNED NOT NULL,
  description TEXT NULL,
  category VARCHAR(120) NULL,
  document_number VARCHAR(120) NULL,
  document_year SMALLINT UNSIGNED NULL,
  access_level ENUM('public','internal','restricted','confidential') NOT NULL DEFAULT 'internal',
  tags_json JSON NULL,
  created_at DATETIME NOT NULL,
  updated_at DATETIME NOT NULL,
  UNIQUE KEY uk_drive_item_metadata_item (item_id),
  KEY idx_drive_item_metadata_category (category),
  KEY idx_drive_item_metadata_year (document_year),
  KEY idx_drive_item_metadata_access (access_level),
  CONSTRAINT fk_drive_item_metadata_item FOREIGN KEY (item_id) REFERENCES drive_items(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;