SQLD 기출문제 예상문제 234번

다음 문제를 풀어보세요.

다음 중 아래 두 SQL 문의 실행 결과에 대한 설명으로 가장 적절한 것을 고르시오.

[테이블 구조]

-- EMPLOYEES 테이블
CREATE TABLE EMPLOYEES (
    EMP_ID    NUMBER PRIMARY KEY,
    EMP_NAME  VARCHAR2(100),
    DEPT_ID   NUMBER
);

-- DEPARTMENTS 테이블
CREATE TABLE DEPARTMENTS (
    DEPT_ID    NUMBER PRIMARY KEY,
    DEPT_NAME  VARCHAR2(100)
);

[데이터]

-- EMPLOYEES 데이터
INSERT INTO EMPLOYEES (EMP_ID, EMP_NAME, DEPT_ID) VALUES (101, '김철수', 10);
INSERT INTO EMPLOYEES (EMP_ID, EMP_NAME, DEPT_ID) VALUES (102, '이영희', 20);
INSERT INTO EMPLOYEES (EMP_ID, EMP_NAME, DEPT_ID) VALUES (103, '박민수', 10);
INSERT INTO EMPLOYEES (EMP_ID, EMP_NAME, DEPT_ID) VALUES (104, '최지영', 30); -- DEPARTMENTS 테이블에 DEPT_ID 30 없음
INSERT INTO EMPLOYEES (EMP_ID, EMP_NAME, DEPT_ID) VALUES (105, '정수진', NULL); -- DEPT_ID가 NULL

-- DEPARTMENTS 데이터
INSERT INTO DEPARTMENTS (DEPT_ID, DEPT_NAME) VALUES (10, '영업부');
INSERT INTO DEPARTMENTS (DEPT_ID, DEPT_NAME) VALUES (20, '개발부');
INSERT INTO DEPARTMENTS (DEPT_ID, DEPT_NAME) VALUES (40, '인사부'); -- EMPLOYEES 테이블에 DEPT_ID 40 없음

[SQL 쿼리]

-- SQL 1
SELECT E.EMP_NAME, D.DEPT_NAME
FROM EMPLOYEES E INNER JOIN DEPARTMENTS D
ON E.DEPT_ID = D.DEPT_ID;

-- SQL 2
SELECT E.EMP_NAME, D.DEPT_NAME
FROM EMPLOYEES E LEFT JOIN DEPARTMENTS D
ON E.DEPT_ID = D.DEPT_ID;