[MySQL] 프로그래머스 273712. 업그레이드 할 수 없는 아이템 구하기

https://school.programmers.co.kr/learn/courses/30/lessons/273712

프로그래머스

정답 코드

SELECT ITEM_INFO.ITEM_ID, ITEM_INFO.ITEM_NAME, ITEM_INFO.RARITY
FROM ITEM_INFO 
LEFT JOIN ITEM_TREE ON ITEM_INFO.ITEM_ID = ITEM_TREE.PARENT_ITEM_ID
WHERE ITEM_TREE.PARENT_ITEM_ID IS NULL
ORDER BY ITEM_INFO.ITEM_ID DESC;

SELECT ITEM_INFO.ITEM_ID, ITEM_INFO.ITEM_NAME, ITEM_INFO.RARITY
FROM ITEM_INFO
WHERE ITEM_INFO.ITEM_ID NOT IN (
    SELECT DISTINCT ITEM_TREE.PARENT_ITEM_ID
    FROM ITEM_TREE
    WHERE ITEM_TREE.PARENT_ITEM_ID IS NOT NULL
)
ORDER BY ITEM_INFO.ITEM_ID DESC