Using CTEs
Alice wants to know how much Delivr spent per month on average during its early months (before September 2018). You'll need to write two queries to solve this problem:
- A query to calculate cost per month, wrapped in a CTE,
- A query that averages monthly cost before September 2018 by referencing the CTE.
Latihan ini adalah bagian dari kursus
Analyzing Business Data in SQL
Latihan interaktif praktis
Cobalah latihan ini dengan menyelesaikan kode contoh berikut.
SELECT
-- Calculate cost
DATE_TRUNC('month', stocking_date)::DATE AS delivr_month,
___ AS cost
FROM meals
JOIN stock ON meals.meal_id = stock.meal_id
GROUP BY delivr_month
ORDER BY delivr_month ASC;