Urpj2 + function subjects count

[Bloo_uni]

CREATE OR REPLACE FUNCTION F_subj(code_semester number)
RETURN number IS
code_sub NUMBER

BEGIN
      SELECT count(codesub) INTO code_sub FROM Subjects where Semester=code_semester
      RETURN code_sub;
END

---- Function created.

alter function f_subj compile

--- Function altered.

select f_subj(5) from dual

--- Output:

F_SUBJ(5)
----------
4