ต้นทุน

SELECT
  -- Select eatery and calculate total cost
  ___,
  DATE_TRUNC('month', stocking_date) :: DATE AS delivr_month,
  ___ :: FLOAT AS cost
FROM meals
JOIN stock ON meals.meal_id = stock.meal_id
-- Keep only the records after October 2018
WHERE ___
GROUP BY eatery, delivr_month
ORDER BY eatery, delivr_month;