Обсуждение: to_date conversion semantics?

On Monday 20 September 2010 7:20:29 am Colin 't Hart wrote:
> Hi,
>
> I can't find in the Postgresql documentation the semantics that explains
> the following:
>
>
> colin@ruby:~/workspace/eyedb$ psql
> psql (8.4.4)
> Type "help" for help.
>
> colin=> select to_date('731332', 'YYMMDD');
>   to_date
> ------------
>  1974-02-01
> (1 row)
>
> colin=>
>
>
> Thanks,
>
> Colin

http://www.postgresql.org/docs/8.4/interactive/functions-formatting.html

--
Adrian Klaver
adrian.klaver@gmail.com

On 09/20/2010 07:50 AM, Colin 't Hart wrote:
> I must be blind, I can see the syntax but I can't see where it explains
> the wrapping phenomenon that I'm seeing.
>
> Cheers,
>
> Colin
>

My turn to be blind, what wrapping ? :)


--
Adrian Klaver
adrian.klaver@gmail.com

The 32nd of Undecember (!) turning into the 1st of February of the
next year... instead of throwing an exception like I expect.


On 20 September 2010 21:02, Adrian Klaver <adrian.klaver@gmail.com> wrote:
> On 09/20/2010 07:50 AM, Colin 't Hart wrote:
>>
>> I must be blind, I can see the syntax but I can't see where it explains
>> the wrapping phenomenon that I'm seeing.
>>
>> Cheers,
>>
>> Colin
>>
>
> My turn to be blind, what wrapping ? :)
>
>
> --
> Adrian Klaver
> adrian.klaver@gmail.com
>

"Colin 't Hart" <colinthart@gmail.com> writes:
> The 32nd of Undecember (!) turning into the 1st of February of the
> next year... instead of throwing an exception like I expect.

As mentioned previously, to_date isn't the tool to use if you want
a strict conversion --- it's designed to be rather, um, liberal.
Some people think that accepting dates like June 31st is a feature.

            regards, tom lane

On 20/09/10 20:18, Colin 't Hart wrote:
> The 32nd of Undecember (!) turning into the 1st of February of the
> next year... instead of throwing an exception like I expect.

What Tom said, but it's presumably using mktime(...) somewhere internally.

perl -MPOSIX  -e 'print scalar gmtime(mktime(0,0,0,32,13-1,73)),"\n"'
Fri Feb  1 00:00:00 1974

http://perldoc.perl.org/POSIX.html#mktime
http://linux.die.net/man/3/mktime

--
   Richard Huxton
   Archonet Ltd