SQLD(SQL 개발자) 기출 · 집합 연산자

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1. 1.(SELECT TO_CHAR(EMPNO) AS EMPNO, ENAME, SAL
   FROM EMP
   UNION
   SELECT EMPLOYEE_ID AS EMPNO, NAME, SALARY
   FROM EMPLOYEES)
   ORDER BY EMPNO;
2. 2.SELECT TO_CHAR(EMPNO) AS EMPNO, ENAME, SAL
   FROM EMP
   UNION
   SELECT EMPLOYEE_ID, NAME, SALARY
   FROM EMPLOYEES
   ORDER BY EMPNO;
3. 3.SELECT ENAME, SAL
   FROM EMP
   MINUS
   SELECT NAME, SALARY
   FROM EMPLOYEES;
4. 4.SELECT DEPTNO, SUM(SAL) AS SUM_SAL
   FROM EMP
   GROUP BY DEPTNO
   UNION ALL
   SELECT DEPARTMENT_ID, SUM(SALARY)
   FROM EMPLOYEES
   GROUP BY DEPARTMENT_ID;