재구매가 일어난 상품(GROUP BY, HAVING)

https://school.programmers.co.kr/learn/courses/30/lessons/131536

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난이도: 레벨2

 

SELECT USER_ID, PRODUCT_ID
FROM ONLINE_SALE
GROUP BY USER_ID, PRODUCT_ID
HAVING COUNT(*) > 1
ORDER BY USER_ID ASC, PRODUCT_ID DESC;