SQLD 기출문제 예상문제 24번

다음 문제를 풀어보세요.

다음은 온라인 쇼핑몰의 일별 상품 판매 현황을 저장하는 `SALES` 테이블입니다. 특정 날짜의 상품별 판매량을 집계하고, 각 상품을 열로 표시하여 결과를 반환하는 SQL 쿼리를 작성하려고 합니다. 다음 중 가장 효율적인 PIVOT 절을 사용하는 쿼리는 무엇입니까?

CREATE TABLE SALES (
    SALE_DATE DATE,
    PRODUCT_ID VARCHAR2(10),
    QUANTITY NUMBER
);

INSERT INTO SALES VALUES (TO_DATE('2023-10-26', 'YYYY-MM-DD'), 'A001', 10);
INSERT INTO SALES VALUES (TO_DATE('2023-10-26', 'YYYY-MM-DD'), 'B002', 5);
INSERT INTO SALES VALUES (TO_DATE('2023-10-27', 'YYYY-MM-DD'), 'A001', 12);
INSERT INTO SALES VALUES (TO_DATE('2023-10-27', 'YYYY-MM-DD'), 'C003', 8);
INSERT INTO SALES VALUES (TO_DATE('2023-10-28', 'YYYY-MM-DD'), 'B002', 7);
INSERT INTO SALES VALUES (TO_DATE('2023-10-28', 'YYYY-MM-DD'), 'C003', 15);

SELECT * FROM SALES
PIVOT (SUM(QUANTITY) FOR PRODUCT_ID IN ('A001', 'B002', 'C003'))
ORDER BY SALE_DATE;

SELECT SALE_DATE, A001, B002, C003 FROM
(SELECT SALE_DATE, PRODUCT_ID, QUANTITY FROM SALES)
Pivot
(
  SUM(QUANTITY)
  FOR PRODUCT_ID IN ('A001' AS A001, 'B002' AS B002, 'C003' AS C003)
)
ORDER BY SALE_DATE;

SELECT SALE_DATE, A001, B002, C003 FROM
(
  SELECT SALE_DATE, PRODUCT_ID, QUANTITY
  FROM SALES
) PIVOT (SUM(QUANTITY) FOR PRODUCT_ID IN (A001, B002, C003))
ORDER BY SALE_DATE;

SELECT SALE_DATE, A001, B002, C003 FROM
(
  SELECT SALE_DATE, PRODUCT_ID, QUANTITY
  FROM SALES
) PIVOT (SUM(QUANTITY) FOR PRODUCT_ID IN ('A001' AS A001, 'B002' AS B002, 'C003' AS C003))
ORDER BY SALE_DATE;