Generating rows

Question

Hello
This is probably quite straight forward but it's monday morning and my brain hurts...
I have the following table
create table dt_test_dates(id number, eff_date date,ret_month number,ret_day number);
insert into dt_test_dates values(1,to_date('01/01/2000','dd/mm/yyyy'),3,15);
insert into dt_test_dates values(2,to_date('01/01/2000','dd/mm/yyyy'),9,10);
insert into dt_test_dates values(3,to_date('01/01/2000','dd/mm/yyyy'),8,9);I need to generate a date for each year between the eff_date and the current sysdate, on the ret_month and ret_day i.e.
ID Date
1  15/03/2000
1  15/03/2001
1  15/03/2002
1  15/03/2003
1  15/03/2004
1  15/03/2005
2  09/10/2000
2  09/10/2001
2  09/10/2002
2  09/10/2003
2  09/10/2004
2  09/10/2005
3  08/09/2000
3  08/09/2001
3  08/09/2002
3  08/09/2003
3  08/09/2004
3  08/09/2005I generated a pipelined function to generate the dates based on the above criteria but I can't see how to fit it into an sql query to pass the ret_month and re_day for each row in dt_test_dates.
I need to use the output of this statement as part of a subquery for the main SQL statement.
Can anyone help?
David

Answer 1

Invoking pipelined functions is not always obvious, as you've discovered ! Anyway, you basically create a cartesian product as follows:-
SELECT dt.id, ed.column_value
FROM   dt_test_dates dt
,      TABLE( expand_dates( dt.eff_date, dt.ret_month, dt.ret_day ) ) ed;The reason it is not obvious is because you can pass the columns of the DT table as arguments to the pipelined function, which seems counter-intuitive at first, but is similar to the TABLE usage for nested tables in columns. Anyway, here is my implementation of expand_dates:-
CREATE TYPE date_ntt AS TABLE OF DATE;
CREATE FUNCTION expand_dates (
                start_date_in IN DATE,
                ret_month_in  IN NUMBER,
                ret_day_in    IN NUMBER
                ) RETURN date_ntt PIPELINED AS
   v_year     INTEGER := EXTRACT( YEAR FROM start_date_in );
   v_year_end INTEGER := EXTRACT( YEAR FROM SYSDATE );
   v_date     DATE    := ADD_MONTHS( start_date_in, ret_month_in-1 ) + ( ret_day_in-1 );
BEGIN
   WHILE v_year <= v_year_end LOOP
      PIPE ROW ( v_date );
      v_date := ADD_MONTHS( v_date, 12 );
      v_year := EXTRACT( YEAR FROM v_date );
   END LOOP;
   RETURN;
END expand_dates;You might want some NVLs depending on your preferences and your data.
Regards
Adrian