Обсуждение: year and weeknumbers (proposal included)

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year and weeknumbers (proposal included)

От
joost@snow.nl
Дата:
hi,

last year (2002) the date december 31st is in week 1 of 2003.

it is not possible to get this out of a date-column using EXTRACT or
to_char.
         to_char( '2002-12-31', 'WW' ) returns 1, and
         to_char( '2002-12-31', 'YYYY' ) returns 2002 (as expected)!

the format for retrieving the year with respect to week-numbering
could be something like IY, IYY, IYYY, IYYYY.

         to_char( '2002-12-31', 'IYYYY' ) returns 2003.

regards,

Joost Helberg
--
Joost Helberg
Technisch Directeur Snow BV http://snow.nl Tel 0418-653333 Fax 0418-653666
Voorzitter VOSN         http://www.vosn.nl Tel 0418-653336 Fax 0418-653666
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Re: year and weeknumbers (proposal included)

От
Bruno Wolff III
Дата:
On Mon, Jan 27, 2003 at 21:53:27 +0100,
  joost@snow.nl wrote:
> hi,
>
> last year (2002) the date december 31st is in week 1 of 2003.
>
> it is not possible to get this out of a date-column using EXTRACT or
> to_char.
>          to_char( '2002-12-31', 'WW' ) returns 1, and
>          to_char( '2002-12-31', 'YYYY' ) returns 2002 (as expected)!

It is POSSIBLE to do. You can use the fact that the Thursday of a week
is always in the same year as the week number refers to, to get the
correct year. It isn't pretty though and it probably is a good idea to
have a simple way to get the year corresponding to an ISO week.

Re: year and weeknumbers (proposal included)

От
Hans-Jürgen Schönig
Дата:
Hi,

Counting weeks is a very special things because it is not the same in
all countries. As far as I have been told Polish people count weeks not
the way Austrians do it.

On my calendar it says that the first week of the year starts on January
1st. As far as I remember other countries such as Poland start to when
the first full week starts.

Maybe we should verify and document this somewhere.
   Regards,
       Hans


joost@snow.nl wrote:

>hi,
>
>last year (2002) the date december 31st is in week 1 of 2003.
>
>it is not possible to get this out of a date-column using EXTRACT or
>to_char.
>         to_char( '2002-12-31', 'WW' ) returns 1, and
>         to_char( '2002-12-31', 'YYYY' ) returns 2002 (as expected)!
>
>the format for retrieving the year with respect to week-numbering
>could be something like IY, IYY, IYYY, IYYYY.
>
>         to_char( '2002-12-31', 'IYYYY' ) returns 2003.
>
>regards,
>
>Joost Helberg
>
>


--
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Re: year and weeknumbers (proposal included)

От
Joost Helberg
Дата:
Hans,

Just like to_char( date, 'IW' ) refers to ISO Week, I'd like to see a
IYYYY for ISO-year, and I wondered whether anyone else was interested,
or whether I was missing then point. (IYYYY matches %G in Unix strftime).

I know `week' has different meanings in various cultures, there's even
weeks of 6 days (well, long ago)!

But there's only one ISO definition for week.

regards,

Joost

>>>>> "Hans"  writes:   > Date: Thu, 30 Jan 2003 15:15:14 +0100   > From: Hans-Jürgen Schönig <postgres@cybertec.at>
>To: joost@snow.nl, pgsql-bugs@postgresql.org   > Subject: Re: [BUGS] year and weeknumbers (proposal included) 
   > Hi,
   > Counting weeks is a very special things because it is not the same in    > all countries. As far as I have been
toldPolish people count weeks not    > the way Austrians do it. 
   > On my calendar it says that the first week of the year starts on January    > 1st. As far as I remember other
countriessuch as Poland start to when    > the first full week starts. 
   > Maybe we should verify and document this somewhere.
   >     Regards,
   >         Hans

   > joost@snow.nl wrote:
   >> hi,   >>    >> last year (2002) the date december 31st is in week 1 of 2003.   >>    >> it is not possible to get
thisout of a date-column using EXTRACT or   >> to_char.    >> to_char( '2002-12-31', 'WW' ) returns 1, and   >>
to_char('2002-12-31', 'YYYY' ) returns 2002 (as expected)!   >>    >> the format for retrieving the year with respect
toweek-numbering   >> could be something like IY, IYY, IYYY, IYYYY.    >>    >> to_char( '2002-12-31', 'IYYYY' )
returns2003.   >>    >> regards,   >>    >> Joost Helberg   >>    >>  

   > --    > *Cybertec Geschwinde u Schoenig*   > Ludo-Hartmannplatz 1/14, A-1160 Vienna, Austria   > Tel: +43/1/913 68
09;+43/664/233 90 75   > www.postgresql.at <http://www.postgresql.at>, cluster.postgresql.at    >
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<http://kernel.cybertec.at>


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--
Joost Helberg
Technisch Directeur Snow BV http://snow.nl Tel 0418-653333 Fax 0418-653666
Voorzitter VOSN         http://www.vosn.nl Tel 0418-653336 Fax 0418-653666
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