문제 : https://programmers.co.kr/learn/courses/30/lessons/59043# 제출 코드 SELECT DISTINCT ANIMAL_INS.ANIMAL_ID, ANIMAL_INS.NAME FROM ANIMAL_INS LEFT JOIN ANIMAL_OUTS ON ANIMAL_INS.ANIMAL_ID = ANIMAL_OUTS.ANIMAL_ID WHERE ANIMAL_INS.DATETIME > ANIMAL_OUTS.DATETIME ORDER BY ANIMAL_INS.DATETIME
