저자 별 카테고리 별 매출액 집계하기(MYSQL, 다시)

https://school.programmers.co.kr/learn/courses/30/lessons/144856

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-- 코드를 입력하세요
SELECT
  BOOK.AUTHOR_ID, AUTHOR.AUTHOR_NAME, BOOK.CATEGORY, SUM((BOOK.PRICE * BOOK_SALES.SALES)) AS TOTAL_SALES  -- 틀림 1 SUM
FROM BOOK
JOIN (AUTHOR, BOOK_SALES) ON (BOOK.BOOK_ID = BOOK_SALES.BOOK_ID AND BOOK.AUTHOR_ID = AUTHOR.AUTHOR_ID)
WHERE DATE_FORMAT(BOOK_SALES.SALES_DATE, '%Y-%m') = '2022-01'
GROUP BY AUTHOR.AUTHOR_NAME, BOOK.CATEGORY  -- 틀림 2 AUTHOR.AUTHOR_NAME 부재로 
ORDER BY BOOK.AUTHOR_ID ASC, BOOK.CATEGORY DESC