문제설명

문제

답

SELECT auth.AUTHOR_ID AS AUTHOR_ID,
       auth.AUTHOR_NAME AS AUTHOR_NAME,
       book.CATEGORY AS CATEGORY, 
       SUM(book.PRICE * bookSales.SALES) AS TOTAL_SALES
FROM BOOK book,
     AUTHOR auth,
     BOOK_SALES bookSales
WHERE auth.AUTHOR_ID = book.AUTHOR_ID
AND book.BOOK_ID = bookSales.BOOK_ID
AND bookSales.SALES_DATE >= TO_DATE('2022-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
AND bookSales.SALES_DATE < TO_DATE('2022-02-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
GROUP BY auth.AUTHOR_ID,
         auth.AUTHOR_NAME,
         book.CATEGORY
ORDER BY auth.AUTHOR_ID,
         book.CATEGORY DESC;