解答
191
SQL文(クエリ)
WITH master AS ( SELECT user_id , SUM(revenue) AS sum_rev FROM sample.sales GROUP BY user_id ) SELECT gender_name , MAX(sum_rev) AS max_sum_rev FROM ( SELECT CASE gender WHEN 1 THEN "男性" WHEN 2 THEN "女性" ELSE "不明" END AS gender_name , sum_rev FROM master LEFT JOIN sample.customers USING (user_id) ) GROUP BY gender_name