[Programmers] 자동차 평균 대여 기간 구하기

문제 링크

정답

-- CAR_RENTAL_COMPANY_RENTAL_HISTORY: HISTORY_ID, CAR_ID, START_DATE, END_DATE

SELECT
    CAR_ID, 
    ROUND(AVG(DATEDIFF(END_DATE, START_DATE) + 1), 1) AS AVERAGE_DURATION
FROM CAR_RENTAL_COMPANY_RENTAL_HISTORY
GROUP BY CAR_ID
HAVING AVG(DATEDIFF(END_DATE, START_DATE) + 1) >= 7
ORDER BY 2 DESC, 1 DESC;

✅ Point

• 대여 기간: DATEDIFF() + 1
• GROUP BY + AVG 로 한 번에 자동차 ID 별 평균 값 구하기