SQLD 기출문제 예상문제 12번

다음 문제를 풀어보세요.

다음 중 아래 테이블과 데이터를 이용했을 때, 쿼리 실행결과가 다른 것을 고르시오.

CREATE TABLE CUSTOMER (
    CUSTOMER_ID INT PRIMARY KEY,
    CUSTOMER_NAME VARCHAR(50)
);

CREATE TABLE ORDERS (
    ORDER_ID INT PRIMARY KEY,
    CUSTOMER_ID INT,
    ORDER_DATE DATE,
    ORDER_AMOUNT DECIMAL(10, 2)
);

INSERT INTO CUSTOMER VALUES ( 1, 'A');
INSERT INTO CUSTOMER VALUES ( 2, 'B');
INSERT INTO CUSTOMER VALUES ( 3, 'C');

INSERT INTO ORDERS VALUES ( 1, 2, '20230101', 10);
INSERT INTO ORDERS VALUES ( 2, 3, '20230102', 20);
INSERT INTO ORDERS VALUES ( 3, 2, '20230105',  5);

SELECT C.CUSTOMER_ID,
       NVL(SUM(O.ORDER_AMOUNT), 0) AS TOTAL_ORDER_AMOUNT
  FROM CUSTOMER C, ORDERS O 
 WHERE C.CUSTOMER_ID = O.CUSTOMER_ID(+)
 GROUP BY C.CUSTOMER_ID
 ORDER BY SUM(O.ORDER_AMOUNT) DESC

 SELECT C.CUSTOMER_ID,
        NVL(SUM(O.ORDER_AMOUNT), 0) AS TOTAL_ORDER_AMOUNT
  FROM CUSTOMER C, ORDERS O 
 WHERE C.CUSTOMER_ID = O.CUSTOMER_ID(+)
 GROUP BY C.CUSTOMER_ID
 ORDER BY TOTAL_ORDER_AMOUNT DESC

SELECT C.CUSTOMER_ID,
        SUM(O.ORDER_AMOUNT) AS TOTAL_ORDER_AMOUNT
  FROM CUSTOMER C, ORDERS O 
 WHERE C.CUSTOMER_ID = O.CUSTOMER_ID(+)
 GROUP BY C.CUSTOMER_ID
 ORDER BY NVL(TOTAL_ORDER_AMOUNT, 0) DESC

 SELECT C.CUSTOMER_ID,
        SUM(NVL(O.ORDER_AMOUNT, 0)) AS TOTAL_ORDER_AMOUNT
  FROM CUSTOMER C, ORDERS O 
 WHERE C.CUSTOMER_ID = O.CUSTOMER_ID(+)
 GROUP BY C.CUSTOMER_ID
 ORDER BY TOTAL_ORDER_AMOUNT DESC