Is this decision correct? PL/SQL - database

Question

Can anyone help me with the following task:
Create a procedure SectionCount(instructor_ID) that, according to the instructor's ID, displays the numbers of those of its sections with the largest number of students enrolled. Display appropriate messages if an instructor with such an ID does not exist or if there are no sections to lead. Add a block to handle the necessary exceptions.
my solution is the following..whether it is correct:
CREATE OR REPLACE FUNCTION your_function_name(i_student_id NUMBER)
RETURN NUMBER AS v_sections_count NUMBER;
BEGIN
SELECT COUNT(SECTION_ID) into v_sections_count FROM ENROLLMENT WHERE STUDENT_ID = i_student_id;
IF v_sections_count > 3 THEN
RETURN -1;
ELSE
RETURN v_sections_count;
END IF;
EXCEPTION WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('An error occured.');
RETURN -2;
END;

Answer 1

A suggestion or two, if I may.
always use table's alias when referencing columns. In your case, that's only one table but - often you have to "fix" a query and add yet another table, and then you don't know which column belongs to which table and have to add aliases anyway.
try to use only one RETURN per function (two, if there's an exception handling section - as in your function) because you might do something wrong in code logic and RETURN (i.e. terminate further execution) although you didn't actually want to do that. Instead, add a new variable which will be used to "calculate" the return value (such as retval in code I posted); then return its value
DBMS_OUTPUT.PUT_LINE is OK for debugging; nobody else will ever see it, because end users won't call that function from SQL*Plus (or other tools which are capable of displaying that message). For example, it (DBMS_OUTPUT.PUT_LINE) won't raise error in Oracle Apex or Oracle Forms, but you won't see anything.
Also, add SQLERRM which will actually show you which error happened. Info "an error occurred" isn't very descriptive
So:
CREATE OR REPLACE FUNCTION your_function_name (i_student_id NUMBER)
RETURN NUMBER
AS
v_sections_count NUMBER;
retval NUMBER;
BEGIN
SELECT COUNT(e.section_id)
INTO v_sections_count
FROM enrollment e
WHERE e.student_id = i_student_id;
retval := CASE WHEN v_sections_count > 3 then -1
ELSE v_sections_count
END;
RETURN retval;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('An error occured: ' || SQLERRM);
retval := -2;
RETURN retval;
END your_function_name ;