2020_상반기_넷마블_SQL

27 Jun 2020

Reading time ~1 minute

문제 풀이

하나의 테이블에서 WHERE절 + 간단한 함수(not in)와 ORDER BY 이용

Code Snippets

select id from game_users
    where id not in (select id1 from friends)
    and id not in (select id2 from friends)
    order by id;

Improvements

select id from game_users
    where id not in (select distinct id1 from friends)
    and id not in (select distinct id2 from friends)
    order by id;

비교할 id1과 id2의 중복을 제거하여 비교할 대상을 줄여 성능향상가능하다고 생각한다.