프로그래머스_Lv3 카테고리 별 도서 판매량 집계하기

문제

 

답변

SELECT A.CATEGORY , SUM(B.SALES) AS TOTAL_SALES FROM BOOK AS A
RIGHT JOIN BOOK_SALES AS B ON A.BOOK_ID=B.BOOK_ID
WHERE DATE_FORMAT(B.SALES_DATE,"%Y-%m-%d") LIKE "%2022-01%"
GROUP BY A.CATEGORY
ORDER BY A.CATEGORY

 

RIGHT JOIN을 활용하여 풀었다