[프로그래머스/Oracle] Lv3. 카테고리 별 도서 판매량 집계하기

| 문제

https://school.programmers.co.kr/learn/courses/30/lessons/144855

프로그래머스

 

| 풀이

SELECT B.CATEGORY AS CATEGORY, SUM(S.SALES) AS TOTAL_SALES
FROM BOOK B JOIN BOOK_SALES S
ON B.BOOK_ID = S.BOOK_ID
WHERE TO_CHAR(S.SALES_DATE, 'YYYY-MM') = '2022-01'
GROUP BY B.CATEGORY
ORDER BY CATEGORY;