write function in PL/SQL to Sum within the same table - sqlplus

Question

I am trying to write a PL/SQL function name hoursWorked that takes workerId and prjId and returns total amount of hours worker has worked on a project.
Table named PROJECTHOURS
WORKERPRJID | WORKERID | PRJID | TOTHOURS | CDATE
---------- ---------- ---------- ---------- ---------
1 1 1 10 1-JAN-14
2 1 1 7 2-JAN-14
3 1 1 6 4-JAN-14
4 2 1 5 11-JAN-14
5 2 1 9 15-JAN-14
6 2 1 7 13-JAN-14
7 1 2 5 11-JAN-14
8 2 2 9 15-JAN-14
9 2 2 7 13-JAN-14
I have tried the following:
CREATE OR replace PROCEDURE Hoursworked (j IN NUMBER,
n IN NUMBER)
IS
hours_worked projecthours.tothours%TYPE := 0;
BEGIN
SELECT workerid,
prjid,
SUM(tothours)
INTO hours_worked
FROM projecthours
WHERE workerid = j
AND prjid = n
GROUP BY j,
n;
RETURN hours_worked;
END;
SQL> show errors;
Errors for PROCEDURE HOURSWORKED:
LINE/COL ERROR
-------- -----------------------------------------------------------------
6/1 PL/SQL: SQL Statement ignored
6/52 PL/SQL: ORA-00947: not enough values
12/1 PL/SQL: Statement ignored
12/1 PLS-00372: In a procedure, RETURN statement cannot contain an
expression
Admittedly I am very inexperienced with SQL in general, so any insights are very welcome, as to what I am doing wrong.

Answer 1

The select is wrong, you select 3 values, but fetch into only one. The group by references are incorrect.
You don't need to select the workerid or the project id, neither do you need the group by.
Should be like below
CREATE OR replace PROCEDURE Hoursworked (j IN NUMBER,
n IN NUMBER,
hours_worked OUT NUMBER)
IS
BEGIN
SELECT SUM(tothours)
INTO hours_worked
FROM projecthours
WHERE workerid = j
AND prjid = n;
END;
In a procedure Return immediately ends program execution, and doesn't expect any parameters. Either change the program unit type to a function, or use OUT variables as above.
And please give better parameter names than "j" & "n"