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