Converting Timestamp to date.

[Yash3]

Hey
I am trying this
create or replace FUNCTION DatesPast
(
v_dueDate Timestamp
)
RETURN NUMBER
AS
DaysPast DATE
BEGIN
TO_DATE(v_dueDate; 'yyyymmdd');
IF (v_dueDate > SYSDATE) THEN
DaysPast :=SYSDATE - v_dueDate ;
END IF;
RETURN DaysPast;
END

I have to convert input date of type timestamp to date type than subtract it from sysdate.and get the result of differnece between days only.
But i get error msg that to_date() is invalid.
I know syntax is wrong somewhere.Can nyone guide me through this.

[Yash3]

return Number is wrong for now.It should be RETURN DATE

[debasisdas]

create or replace FUNCTION DatesPast
(
v_dueDate Timestamp
)
RETURN number
AS
dd date;
DaysPast number;
BEGIN
select trunc(cast(v_dueDate as timestamp)) into dd from dual;
IF (dd > SYSDATE) THEN
DaysPast :=dd-SYSDATE ;
RETURN DaysPast;
else
DaysPast :=dd-sysdate ;
RETURN DaysPast;
END IF;
END;
 

Hope that is what you were looking for.