text: --count the actual unique menus each dish appears in and compare with menus_appeared
  SELECT * FROM (
  	SELECT d.*, COUNT(DISTINCT mp.menu_id) AS menus_appeared_calc
  	FROM Dish d
  	INNER JOIN MenuItem mi ON mi.dish_id=d.id
  	INNER JOIN MenuPage mp ON mp.id=mi.menu_page_id
  	GROUP BY d.id
  )
  WHERE menus_appeared != menus_appeared_calc
  