text: --1--
  SELECT DISTINCT EMPLE.OFICIO, DEPART.LOC
  FROM EMPLE, DEPART
  WHERE EMPLE.DEPT_NO = 10
  AND EMPLE.DEPT_NO = DEPART.DEPT_NO;
  
  --2--
  SELECT DEPART.DEPT_NO, DEPART.DNOMBRE, COUNT(EMPLE.EMP_NO) AS "NUMERO DE EMPLEADOS"
  FROM EMPLE, DEPART
  WHERE EMPLE.DEPT_NO(+) = 10
  GROUP BY DEPART.DEPT_NO, DEPART.DNOMBRE
  ORDER BY DEPART.DEPT_NO;
  
  --3--
  SELECT EMPLE.DEPT_NO, DNOMBRE, COUNT(*) "NUMERO DE EMPLEADOS"
  FROM EMPLE, DEPART
  WHERE EMPLE.DEPT_NO = DEPART.DEPT_NO
  GROUP BY EMPLE.DEPT_NO, DNOMBRE
  HAVING COUNT(*) = (SELECT MAX(COUNT(*))
                    FROM EMPLE
                    GROUP BY DEPT_NO);
                    
  --4--
  SELECT E.APELLIDO, D.DNOMBRE "NOMBRE DEPARTAMENTO", E.SALARIO
  FROM EMPLE E, DEPART D
  WHERE E.DEPT_NO = D.DEPT_NO
  AND (SALARIO, NVL(COMISION_PCT, -1))
      IN (SELECT SALARIO, NVL(COMISION_PCT, -1)
          FROM EMPLE E, DEPART D
          WHERE E.DEPT_NO = D.DEPT_NO
          AND UPPER(LOC) = 'BARCELONA');