[SQL문제풀기] 업그레이드 할 수 없는 아이템 구하기

문제

MYSQL

내가 작성한 정답

#1
SELECT P.ITEM_ID, I.ITEM_NAME, I.RARITY
FROM ITEM_TREE P
LEFT JOIN ITEM_TREE D ON P.ITEM_ID = D.PARENT_ITEM_ID
JOIN ITEM_INFO I ON P.ITEM_ID = I.ITEM_ID
WHERE D.ITEM_ID IS NULL
ORDER BY 1 DESC;

#2
SELECT T.ITEM_ID, I.ITEM_NAME, I.RARITY
FROM ITEM_TREE T  
JOIN ITEM_INFO I ON T.ITEM_ID = I.ITEM_ID
WHERE I.ITEM_ID NOT IN (SELECT DISTINCT PARENT_ITEM_ID FROM ITEM_TREE WHERE PARENT_ITEM_ID IS NOT NULL )
ORDER BY 1 DESC;