[SQL문제풀기 - Advent of SQL 2025 🎅] 도시별 VIP 고객 찾기

문제

solvesql.com

https://solvesql.com/problems/vip-of-cities/

내가 작성한 정답

MySQL, PostgreSQL, SQLite

with a as (select city_id, customer_id, sum(total_price)-sum(discount_amount) total_spent
          from transactions
          where not is_returned
          group by city_id, customer_id)
select city_id, customer_id, total_spent
from a 
where (city_id, total_spent) in (select city_id, max(total_spent) from a group by city_id)
order by 1;