From: Ireneusz Pluta <ipluta@wp.pl>
To: Sergey Konoplev <gray.ru@gmail.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Week to date function
Date: Fri, 26 Mar 2010 12:47:13 +0100
Message-ID: <4BAC9EC1.7010708@wp.pl> (raw)
In-Reply-To: <c3a7de1f1003260402y42a61ca4j657983343760d4d4@mail.gmail.com>
References: <4BAB2C15.8090406@wp.pl>
<c3a7de1f1003250244p440b8244t57319b742fa680f0@mail.gmail.com>
<4BAC9107.5070701@wp.pl>
<c3a7de1f1003260402y42a61ca4j657983343760d4d4@mail.gmail.com>
Sergey Konoplev pisze:
>> CREATE OR REPLACE FUNCTION your_week2date(double precision, double
>> precision) RETURNS SETOF date
>> AS
>> $_$
>> SELECT day
>> FROM (
>> SELECT (
>> date_trunc('week', ($1::text||'-01-01')::date)
>> + ($2::text||' week')::interval
>> + ( d::text||' day')::interval
>> )::date AS day
>> FROM generate_series(0, 6) AS d
>> ) alias
>> WHERE to_char(day, 'IYYY')::integer = $1
>> ORDER
>> BY 1
>> $_$
>> LANGUAGE SQL
>> IMMUTABLE
>>
>
> I think it is better to use date_part('year', day) instead of
> to_char(...).
this might cut first or last week in the year, like this:
SELECT your_week2date(2009, 52) ;
your_week2date
----------------
2009-12-28
2009-12-29
2009-12-30
2009-12-31
2010-01-01 cut
2010-01-02 cut
2010-01-03 cut
(7 rows)
which is not what I want when playing with isoweeks.
> And may be it is worth to do raise exception when
> incorrect week specified.
>
but, maybe, controlled by an additonal parameter saying if one prefers
to have exception or rather an empty resultset
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To: pgsql-sql@postgresql.org
Cc: ipluta@wp.pl, gray.ru@gmail.com
Subject: Re: Week to date function
In-Reply-To: <4BAC9EC1.7010708@wp.pl>
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