Recursive Sub-query Factoring... bug? or my own personal ignorance?

Question

I was trying to create a list of all dates in the current month using a recursive sub-query factor. (Oracle 11.2)
I know how to do this by other methods; the question is, what's going on with this "WITH" example?
Here's my attempt at generating the list:
with
  date_list ( crnt_mnth_date )  as
    ( select  cast ( trunc(sysdate,'MM') as date )  from dual
      UNION ALL
      select  crnt_mnth_date + interval '1' day
        from  date_list
       where  to_char(crnt_mnth_date,'MM') = to_char(sysdate,'MM')
select  *  from  date_list ;The recursion should add one day to the previous date and continue while the generated dates are in the same month
as the current-date (sysdate). All I get is the first day of the month. In an attempt to figure this out I added the
sequence "n". To my surprise the recursion is subtracting instead of adding the one day each time.
with
  date_list ( n, crnt_mnth_date )  as
    ( select  1,  cast ( trunc(sysdate,'MM') as date )  from dual
      UNION ALL
      select  n+1,  crnt_mnth_date + (interval '1' day)  as crnt_mnth_date
        from  date_list
       where  n < 9
select  *  from  date_list ;And... Changing the "+" to a "-" still subtracts one day each time -- no change.
Obvious BUG? Or am I just confused on how this works?

Answer 1

Hi,
I've heard that the new recursive WITH clause feature is buggy, especially when DATEs are involved.
I get the same (unexpected) results that you do.
A very similar query, using only NUMBERs, does wotk as expected:
with
  date_list ( n, crnt_mnth_num )  as
    ( select  1,  20010501   from dual
      UNION ALL
      select  n+1,  crnt_mnth_num + 1  as crnt_mnth_num
        from  date_list
       where  n < 9
select  *  from  date_list ;Outptu:
`       N CRNT_MNTH_NUM
        1      20010501
        2      20010502
        3      20010503
        4      20010504
        5      20010505
        6      20010506
        7      20010507
        8      20010508
        9      20010509