[GROUP BY/LEVEL3] 카테고리 별 도서 판매량 집계하기 (MySQL)

MySQL

SELECT CATEGORY
, SUM(SALES) AS TOTAL_SALES
FROM BOOK A, BOOK_SALES B 
WHERE A.BOOK_ID = B.BOOK_ID
AND YEAR(SALES_DATE) = 2022
AND MONTH(SALES_DATE) = 1
GROUP BY CATEGORY
ORDER BY CATEGORY