Thread: Strange behaviour of to_date()
I noticed a quite strange behaviour of to_char() in 7.0 and 7.1. It treats
abbreveated forms of a date completely wrong. Example:
-- this one is ok
mario=# select to_date('04.01.2001', 'dd.mm.yyyy'); to_date
------------2001-01-04
-- this is completly wrong, but NO error raised
mario=# select to_date('4.01.2001', 'dd.mm.yyyy'); to_date
------------0001-01-04
-- completly wrong as well
mario=# select to_date('4.1.2001', 'dd.mm.yyyy'); to_date
------------0001-01-04
IMO to_date() should either recognize the date, even if shorter than the mask
(Oracle compatible), or raise an error. Currently it gives completly wrong
results, which is the worst option.
I tried to fix this myself, but I'm lost within backend/utils/adt/formatting.c
--
===================================================Mario Weilguni KPNQwest Austria GmbH
Senior Engineer Web Solutions Nikolaiplatz 4
tel: +43-316-813824 8020 graz, austria
fax: +43-316-813824-26 http://www.kpnqwest.at
e-mail: mario.weilguni@kpnqwest.com
===================================================
On Tue, Apr 17, 2001 at 07:46:19PM +0200, Mario Weilguni wrote:
> I noticed a quite strange behaviour of to_char() in 7.0 and 7.1. It treats
> abbreveated forms of a date completely wrong. Example:
>
> -- this one is ok
> mario=# select to_date('04.01.2001', 'dd.mm.yyyy');
> to_date
> ------------
> 2001-01-04
>
> -- this is completly wrong, but NO error raised
> mario=# select to_date('4.01.2001', 'dd.mm.yyyy');
> to_date
> ------------
> 0001-01-04
>
> -- completly wrong as well
> mario=# select to_date('4.1.2001', 'dd.mm.yyyy');
> to_date
> ------------
> 0001-01-04
Really bug? What you obtain from 'dd.mm.yyyy' in to_char()
test=# select to_char('04.01.2001'::date, 'dd.mm.yyyy'); to_char
------------04.01.2001
(1 row)
'04.01.2001' and '4.1.2001' are *different* strings with *different*
format masks....
See (and read docs):
test=# select to_char('04.01.2001'::date, 'FMdd.FMmm.yyyy');to_char
----------4.1.2001
(1 row)
test=# select to_date('4.1.2001', 'FMdd.FMmm.yyyy'); to_date
------------2001-01-04
(1 row)
Yes, Oracle support using not exact format mask, but Oracle's to_date
is very based on date/time and not support others things:
SVRMGR> select to_date('333.222.4.1.2001', '333.222.FMdd.FMmm.yyyy') from
dual;
TO_DATE('
---------
ORA-01821: date format not recognized
test=# select to_date('333.222.4.1.2001', '333.222.FMdd.FMmm.yyyy'); to_date
------------2001-01-04
(1 row)
or nice:
test=# select to_date('33304333.1.2001', '333dd333.FMmm.yyyy'); to_date
------------2001-01-04
(1 row)
And primarily Oracle's to_date() is designed for operation that in
PG is solved via timestamp/date cast. For example you can use in
Oracle to_date('4.1.2001') without format mask and it's same thing
as 4.1.2001::date cast('4.1.2001' as date) in PG.
The to_char()/to_date() works as say docs :-)
Better support for not exact masks is in my TODO fo 7.2.
Karel
-- Karel Zak <zakkr@zf.jcu.cz>http://home.zf.jcu.cz/~zakkr/C, PostgreSQL, PHP, WWW, http://docs.linux.cz,
http://mape.jcu.cz
Am Mittwoch, 18. April 2001 10:47 schrieben Sie:
(...)
>
> Yes, Oracle support using not exact format mask, but Oracle's to_date
> is very based on date/time and not support others things:
>
> SVRMGR> select to_date('333.222.4.1.2001', '333.222.FMdd.FMmm.yyyy') from
> dual;
> TO_DATE('
> ---------
> ORA-01821: date format not recognized
>
>
> test=# select to_date('333.222.4.1.2001', '333.222.FMdd.FMmm.yyyy');
> to_date
> ------------
> 2001-01-04
> (1 row)
>
> or nice:
>
> test=# select to_date('33304333.1.2001', '333dd333.FMmm.yyyy');
> to_date
> ------------
> 2001-01-04
> (1 row)
Maybe it's not designed for my needs, but that does not change the fact that
it's a bug. When the mask is not exact, it should raise an error, and not
silently return WRONG values, which is really bad behaviour, and will result
in "lost" data.
--
===================================================Mario Weilguni KPNQwest Austria GmbH
Senior Engineer Web Solutions Nikolaiplatz 4
tel: +43-316-813824 8020 graz, austria
fax: +43-316-813824-26 http://www.kpnqwest.at
e-mail: mario.weilguni@kpnqwest.com
===================================================