SQL 알고리즘 코드카타 20일차(4) 26.01.18(일)

부제:

자동차 평균 대여 기간 구하기, 레벨 4

 

1. 문제 링크:https://school.programmers.co.kr/learn/courses/30/lessons/157342
2. 정답 코드: 

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 average_duration >= 7
order by
    average_duration desc,
    car_id desc

3. 오류 상황:

SELECT
    car_id,
    round(avg(datediff(end_date, start_date)+1), 1) as average_duration
from car_rental_company_rental_history
having average_duration >= 7
order by
    average_duration desc,
    car_id desc

=> 그룹화 누락

4. 시도 방법: 그룹화 추가
5. 최종 문제 해결 방법: 자동차 ID를 기준으로 그룹화한다. GROUP BY 절에 CAR_ID 추가