解答
145
SQL文(クエリ)
WITH master AS ( SELECT user_id , COUNT(DISTINCT order_id) AS orders FROM sample.sales GROUP BY user_id ) SELECT CASE gender WHEN 1 THEN "男性" WHEN 2 THEN "女性" ELSE NULL END AS gender_cat , SUM(orders) AS sum_orders FROM master LEFT JOIN sample.customers USING (user_id) GROUP BY gender_cat ORDER BY sum_orders DESC