Re: find last day of month

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От Chris Browne
Тема Re: find last day of month
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Msg-id 607jaehv8c.fsf@dba2.int.libertyrms.com
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Ответ на find last day of month  ("Andrus Moor" <eetasoft@online.ee>)
Ответы Re: find last day of month  (Sven Willenberger <sven@dmv.com>)
Список pgsql-general
"Andrus Moor" <eetasoft@online.ee> writes:

> I have a table containing month column in format mm.yyyy
>
> create table months ( tmkuu c(7));
> insert into months values ('01.2005');
> insert into months values ('02.2005');
>
> How to create select statement which converts this column to date type
> containing last day of month like
>
> '2005-01-31'
> '2005-02-28'

The usual trick is to split it into year and month, add 1 to the
month, if that's > 12, jump to 1, and add a year.

Based on those...  Construct the first day of the NEXT month.

Thus...  01.2005
 --> month = 2
 --> year = 2005

Construct first day of the next month:
   2005-02-01

Now, subtract a day from that, and you'll get the final day of the
present month.

That approach will nicely cope with leap years and such.
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