text: DO $$
  BEGIN
      IF NOT EXISTS (SELECT 1 FROM pg_type WHERE typname = 'playlist_smart_order') THEN
          CREATE TYPE playlist_smart_order AS
          ENUM('oldest', 'newest');
      END IF;
  	IF NOT EXISTS (SELECT 1 FROM pg_type WHERE typname = 'playlist_smart_limit_type') THEN
          CREATE TYPE playlist_smart_limit_type AS
          ENUM('songs', 'duration');
      END IF;
  END$$;
  ALTER TABLE playlist ADD COLUMN IF NOT EXISTS flag_smartlimit BOOLEAN DEFAULT(false);
  ALTER TABLE playlist ADD COLUMN IF NOT EXISTS smart_limit_number INTEGER DEFAULT(0);
  ALTER TABLE playlist ADD COLUMN IF NOT EXISTS smart_limit_order playlist_smart_order DEFAULT('newest');
  ALTER TABLE playlist ADD COLUMN IF NOT EXISTS smart_limit_type playlist_smart_limit_type DEFAULT('songs');