[SQL_Level3] 카테고리 별 도서 판매량 집계하기

문제 설명

문제

예시

나의 풀이

# SUM(), MONTH(), JOIN&ON절 사용 
SELECT CATEGORY, SUM(SALES) AS TOTAL_SALES
FROM BOOK_SALES JOIN BOOK ON BOOK_SALES.BOOK_ID = BOOK.BOOK_ID
WHERE MONTH(SALES_DATE) = 1
GROUP BY CATEGORY
ORDER BY CATEGORY

# SUM(), MONTH() 사용
SELECT CATEGORY, SUM(SALES) AS TOTAL_SALES
FROM BOOK_SALES, BOOK
WHERE BOOK_SALES.BOOK_ID=BOOK.BOOK_ID AND MONTH(SALES_DATE) = 1
GROUP BY CATEGORY
ORDER BY CATEGORY