Re: Extracting data by months - Mailing list pgsql-sql

From Daniel Kalchev
Subject Re: Extracting data by months
Date
Msg-id 200008040553.IAA27141@dcave.digsys.bg
Whole thread Raw
In response to Re: Extracting data by months  (John McKown <jmckown@prodigy.net>)
List pgsql-sql
Actually, PostgreSQL has specific function for this purpose. The query would 
be:

SELECT * FROM table WHERE date_part('month', date_field) = '8';

(example to select month 8)

If you use date_trunc, the selection will be by month/year - that is, 
date_trunc('month', date_field) will always result in the 1st monthday of the 
month. The year will be preserved.

Daniel

>>>John McKown said:> This might seem rather silly, but could you simply do something like:> > select * from database>
     where date_field >= '01/01/2000'::date>        and   date_field < '02/01/2000'::date;> > Of course, if date_field
couldcontain many different years, then this> would not get you the result you wanted.> > John> > On Thu, 3 Aug 2000,
AnttiLinno wrote:> > > Lo.> > > >  I'm in dire need of knowledge, how to extract data by month. Monthday> > and year
arent'important, those I can't give from perl script, but what> > I do give to postgres are the numbers of the months.
Datefield is in> > timestamp. I thought about date_trunc, but I can't think of, how to get> > data with it. In script
willbe 12 queries, for each month, to get the> > news from that month.  > > Btw, is there somewhere a manual about
date_trunc,the docs that come with> > RH6.1 distribution are somewhat short and lacking explanation of> > date_trunc.>
>Antti> > > > > 
 




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