Sub queries in Having Clause oracle

SELECT Deptno, MIN(Sal)

FROM Emp

GROUP BY Deptno

HAVING  MIN(Sal) > (SELECT

                    MIN(Sal)

                    FROM Emp

                    WHERE  Deptno = 20);

                   

SELECT Job, AVG(Sal)

FROM Emp

GROUP BY Job

HAVING AVG(Sal) =  (SELECT

                    MIN(Avg(Sal))

                    FROM Emp

                    GROUP BY Job);

SELECT Job, AVG(Sal)

FROM Emp

GROUP BY Job

HAVING AVG(Sal) < (SELECT

                    MAX(AVG(Sal))

                    FROM Emp

                    GROUP BY Job);

SELECT Job, AVG(Sal),

TO_CHAR(AVG (Sal), 'L99,999.99')

FROM Emp

GROUP BY Job

HAVING  AVG(Sal) < (SELECT

MAX(AVG(Sal))

FROM Emp

GROUP BY Deptno);