ALTER TABLE enclosures RENAME TO _enclosures_old;

CREATE TABLE enclosures (
	article_id TEXT PRIMARY KEY NOT NULL REFERENCES articles(article_id),
	url TEXT NOT NULL,
	mime_type TEXT,
    title Text,
    position DOUBLE default null
);

INSERT OR REPLACE INTO enclosures (article_id, url, mime_type, title, position)
  SELECT article_id, url, mime_type, title, position
  FROM _enclosures_old;

DROP TABLE _enclosures_old;