解答
144
SQL文(クエリ)
WITH master AS ( SELECT user_id , product_id , SUM(revenue) AS sum_rev FROM sample.sales GROUP BY user_id , product_id ) SELECT product_id , SUM(sum_rev) AS sum_rev FROM master JOIN sample.customers USING (user_id) WHERE DATE_DIFF("2019-12-31", birthday, YEAR) >= 50 GROUP BY product_id ORDER BY sum_rev DESC LIMIT 3