아찌방 하우스

https://school.programmers.co.kr/learn/courses/30/lessons/151139

풀이 - 나의 생각

먼저 8~10월 총 대여 횟수가 5회 이상인 CAR_ID를 찾아낸 후

JOIN한다.

그 후에 GROUP BY로 달 별, CAR_ID 별로 묶어서

그 숫자를 센다.

코드

SELECT MONTH(START_DATE) MONTH, C.CAR_ID, COUNT(*) RECORDS
FROM CAR_RENTAL_COMPANY_RENTAL_HISTORY C
JOIN (
    SELECT CAR_ID
    FROM CAR_RENTAL_COMPANY_RENTAL_HISTORY
    WHERE MONTH(START_DATE) IN (8, 9, 10)
    GROUP BY CAR_ID
    HAVING COUNT(HISTORY_ID) >= 5) SUB ON C.CAR_ID = SUB.CAR_ID
WHERE MONTH(START_DATE) IN (8, 9, 10)
GROUP BY MONTH, C.CAR_ID
HAVING COUNT(*) >= 1
ORDER BY MONTH, C.CAR_ID DESC;

https://school.programmers.co.kr/learn/courses/30/lessons/77487

풀이 - 나의 생각

서브쿼리를 조인하여 문제를 해결했습니다.

코드

SELECT P.*
FROM PLACES P
JOIN (
    SELECT HOST_ID
    FROM PLACES
    GROUP BY HOST_ID
    HAVING COUNT(*) > 1
) Sub ON P.HOST_ID = Sub.HOST_ID
ORDER BY P.ID;

https://school.programmers.co.kr/learn/courses/30/lessons/164671

풀이 - 나의 생각

코드

SELECT CONCAT('/home/grep/src/',BOARD_ID,'/',FILE_ID,FILE_NAME,FILE_EXT) FILE_PATH
FROM USED_GOODS_FILE
WHERE BOARD_ID LIKE (
    SELECT BOARD_ID
    FROM USED_GOODS_BOARD
    ORDER BY VIEWS DESC
    LIMIT 1
)
ORDER BY FILE_ID DESC