카테고리 별 도서 판매량 집계하기
SELECT B.CATEGORY, SUM(S.SALES) AS TOTAL_SALES
FROM BOOK_SALES S
LEFT JOIN BOOK B
ON B.BOOK_ID = S.BOOK_ID
WHERE YEAR(S.SALES_DATE) = 2022
AND MONTH(S.SALES_DATE) = 1
GROUP BY 1
ORDER BY 1 ASC
;SELECT B.CATEGORY, SUM(S.SALES) AS TOTAL_SALES
FROM BOOK_SALES S
LEFT JOIN BOOK B
ON B.BOOK_ID = S.BOOK_ID
WHERE YEAR(S.SALES_DATE) = 2022
AND MONTH(S.SALES_DATE) = 1
GROUP BY 1
ORDER BY 1 ASC
;