• 1번 문제

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    COMM AS 커미션,
    (SAL + COMM) AS 총액
FROM
    EMP
WHERE
    COMM IS NOT NULL  -- 커미션이 NULL이 아닌 사람만 포함
ORDER BY
    총액 DESC;        -- 총액이 많은 순서로 정렬

• 2번

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    (SAL * 0.13) AS 보너스_금액,
    DEPTNO AS 부서번호
FROM
    EMP
WHERE
    DEPTNO = 10;

• 3번

SELECT
    ENAME AS 이름,
    DEPTNO AS 부서번호,
    SAL AS 급여,
    (SAL * 12) + (SAL * 1.5) AS 연봉
FROM
    EMP
WHERE
    DEPTNO = 30;

• 4번

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    ROUND(SAL / (12 * 5), 0) AS 시간당_임금  -- ROUND(값, 0)는 소수점 첫째 자리에서 반올림
FROM
    EMP
WHERE
    DEPTNO = 20;

• 5번

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    ROUND(SAL * 0.15, 1) AS 회비  -- 소수점 두 자리에서 반올림하려면 첫째 자리까지 표시 (예: 123.45 -> 123.5)
FROM
    EMP
WHERE
    SAL BETWEEN 1500 AND 3000;

• 6번

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    TRUNC(SAL * 0.15) AS 경조비
FROM
    EMP
WHERE
    SAL >= 2000;

• 7번

SELECT
    DEPTNO AS 부서번호,
    ENAME AS 이름,
    HIREDATE AS 입사일,
    SYSDATE AS 현재일,
    TRUNC(SYSDATE - HIREDATE) AS 근무일수_절삭,
    TRUNC(MONTHS_BETWEEN(SYSDATE, HIREDATE) / 12) AS 근무년수,
    TRUNC(MONTHS_BETWEEN(SYSDATE, HIREDATE)) AS 근무월수,
    TRUNC((SYSDATE - HIREDATE) / 7) AS 근무주수
FROM
    EMP;

• 8번

SELECT
    ENAME AS 이름,
    SAL AS 급여,
    (SAL * 0.9) AS 실_수령액
FROM
    EMP
ORDER BY
    SAL DESC;  -- 급여가 많은 순으로 정렬

• 9번

SELECT
    ENAME AS 사원이름,
    HIREDATE AS 입사일,
    (HIREDATE + 90) AS "90일_후의_날",
    SAL AS 급여
FROM
    EMP;

• 10번 문제

SELECT
    ENAME AS 이름,
    HIREDATE AS 입사일,
    ADD_MONTHS(HIREDATE, 6) AS "6개월_후의_날짜",
    SAL AS 급여
FROM
    EMP;