CREATE TABLE taglinks (
  idTag       integer,
  idMedia     integer,
  media_type  text,
  sorting     integer
);

CREATE UNIQUE INDEX ix_taglinks_1
  ON taglinks
  (idTag, media_type, idMedia);

CREATE UNIQUE INDEX ix_taglinks_2
  ON taglinks
  (idMedia, media_type, idTag);

CREATE INDEX ix_taglinks_3
  ON taglinks
  (media_type);

CREATE TRIGGER delete_tag
  AFTER DELETE
  ON taglinks
BEGIN DELETE FROM tag WHERE idTag=old.idTag AND idTag NOT IN (SELECT DISTINCT idTag FROM taglinks);
		END;