SQL/SQL 문제
[HackerRank] Weather Observation Station 4
Lim Seung Hyun
2021. 11. 19. 14:23
문제 : https://www.hackerrank.com/challenges/weather-observation-station-4/problem?isFullScreen=true
Weather Observation Station 4 | HackerRank
Find the number of duplicate CITY names in STATION.
www.hackerrank.com
문제 해설
- 전체 CITY의 수에서 중복을 제거한 CITY의 수의 차이를 조회
풀이 (MySQL)
SELECT COUNT(CITY) - COUNT(DISTINCT(CITY))
FROM STATION728x90