[프로그래머스] 저자 별 카테고리 별 매출액 집계하기

 

# 3개의 테이블을 조인하고 매출액에 sum을 넣는 것 잊지말자

 

SELECT a.AUTHOR_ID, AUTHOR_NAME, CATEGORY, sum(SALES*PRICE) as TOTAL_SALES
from AUTHOR a 
left join BOOK b on a.AUTHOR_ID=b.AUTHOR_ID
left join BOOK_SALES c on b.BOOK_ID=c.BOOK_ID 
where  sales_date like '2022-01-%'
group by a.AUTHOR_ID, CATEGORY
order by a.AUTHOR_ID, CATEGORY desc