[SQL] 해커랭크 SQL Project Planning

SET SQL_MODE = '';
SELECT A.START_DATE, B.END_DATE
  FROM (SELECT START_DATE FROM PROJECTS WHERE START_DATE NOT IN (SELECT END_DATE FROM PROJECTS)) A,
       (SELECT END_DATE FROM PROJECTS WHERE END_DATE NOT IN (SELECT START_DATE FROM PROJECTS)) B
 WHERE A.START_DATE < B.END_DATE
 GROUP BY A.START_DATE
 ORDER BY DATEDIFF(B.END_DATE, A.START_DATE), A.START_DATE

SQL_MODE 초기화 & 조회

 

SQL_MODE를 확인해보자

SHOW VARIABLES LIKE 'SQL_MODE'

SQL_MODE = ONLY_FULL_GROUP_BY 확인

(GROUP BY절에 포함되지 않은 컬럼을 집합함수로 감싸야만 사용할 수 있게 해줌)

해커랭크 SQL Project Planning SQL