[다시보기]- SELECT - 업그레이드된 아이템 구하기

 

https://school.programmers.co.kr/learn/courses/30/lessons/273711

프로그래머스

 

서브 쿼리를 사용한 풀이

SELECT ITEM_ID, ITEM_NAME, RARITY
FROM ITEM_INFO
WHERE ITEM_ID IN (
    SELECT ITEM_ID
    FROM ITEM_TREE
    WHERE PARENT_ITEM_ID IN (
        SELECT ITEM_ID
        FROM ITEM_INFO
        WHERE RARITY="RARE"
    )
)
ORDER BY ITEM_ID DESC;

 

 

3중 join을 사용한 풀이

SELECT C.ITEM_ID, C.ITEM_NAME, C.RARITY
FROM
ITEM_INFO C
JOIN ITEM_TREE B
ON C.ITEM_ID=B.ITEM_ID
JOIN ITEM_INFO A
ON B.PARENT_ITEM_ID=A.ITEM_ID
WHERE A.RARITY="RARE"
ORDER BY ITEM_ID DESC;