Need help to debug a function

Question

Hi Folks,
Can somebody please point out the mistake in the following PL/SQL function
Environment: Oracle 10g (Rel 2)
Error Message:
SQL> show errors
Errors for FUNCTION SECTIONS_TAUGHT:
*13/3 PL/SQL: Statement ignored*
*13/7 PLS-00320: the declaration of the type of this expression is incomplete or malformed*
Code:
SET SERVEROUTPUT ON;
CREATE OR REPLACE FUNCTION sections_taught
*(i_instructor_id IN section.instructor_id%TYPE)*
RETURN VARCHAR2
AS
v_sections_taught     NUMBER;
v_status              VARCHAR2(100);
BEGIN
SELECT count()*
INTO v_sections_taught
FROM section
WHERE INSTRUCTOR_ID = i_instructor_id;
IF (v_sections_taught => 3)
THEN
v_status := 'Instructor: '||i_instructor_id ||' teaches '||v_sections_taught||' sections and needs a break';
ELSE
v_status := 'Instructor: '||i_instructor_id ||' teaches '||v_sections_taught||' sections';
END IF;
RETURN v_status;
EXCEPTION
WHEN OTHERS
THEN
v_status := 'There has been an error in the function !!!';
RETURN v_status;
END;
desc SECTION;
Name                                      Null?    Type
SECTION_ID                                NOT NULL NUMBER(8)
COURSE_NO                                 NOT NULL NUMBER(8)
SECTION_NO                                NOT NULL NUMBER(3)
START_DATE_TIME                                    DATE
LOCATION                                           VARCHAR2(50)
INSTRUCTOR_ID                             NOT NULL NUMBER(8)
CAPACITY                                           NUMBER(3)
CREATED_BY                                NOT NULL VARCHAR2(30)
CREATED_DATE                              NOT NULL DATE
MODIFIED_BY                               NOT NULL VARCHAR2(30)
MODIFIED_DATE                             NOT NULL DATE
Thanks in advance
rogers42

Answer 1

Hi,
Not that you asked, but:
All code should be formatted so that how it appears on the screen somehow reflects what is going on.
For example, in the code below, it's easy to tell
where the DECLARE, BEGIN and EXCEPTION sections start and end,
how many arguments there are,
what the datatype of each variable is
what the scope of the IF statement is
and so on.
This is especially helpful for soemone who is not familiar with your application, such as all the people on the forum who want to help you.
Beware of repetitions in your code. See if there's a better way to avoid them.
For example, depending on the value of v_sections_taught, you might assign two differnt things to v_status. Both of those things involve the same 5-way concatenation. The code below factors that common element out. If you ever want to cahnge that part of the message, you'll only have to change it in one place.
Beware of EXCEPTION WHEN OTHERS.
Normally, when a run-time error occurs, the program stops, and an error message with details about the exact error, and exactly where it occurred, is printed. If you put in you own exception handling mechanism,l you lose all of that. Think carefully about whether you really need to keep going, or if you need to know about the error and fix it.
Granted, sometimes the error messages aren't as accurate or detailed as we'd like, but they're always more informative than 'There has been an error in the function !!!'.
If you really, really must override the detfault error handling, try to make your own as informative as you can. SQLERRM is useful for that.
The code below incorporates the suggestions above:
CREATE OR REPLACE FUNCTION sections_taught
(      i_instructor_id        IN     section.instructor_id%TYPE
RETURN VARCHAR2
AS
     v_sections_taught NUMBER;
     v_status VARCHAR2(100);
BEGIN
     SELECT  count(*)
     INTO      v_sections_taught
     FROM     section
     WHERE     INSTRUCTOR_ID = i_instructor_id;
     v_status := 'Instructor: ' || i_instructor_id
                           || ' teaches '
                       || v_sections_taught
                       || ' sections';
     IF (v_sections_taught >= 3)
     THEN
          v_status := v_status || ' and needs a break';
     END IF;
     RETURN v_status;
EXCEPTION
     WHEN OTHERS
     THEN
          RETURN  'Error in sections_taught: ' || SQLERRM;
END;
/