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From: Sergey Konoplev <gray.ru@gmail.com>
Date: Fri, 26 Mar 2010 14:02:02 +0300
Message-ID: <c3a7de1f1003260402y42a61ca4j657983343760d4d4@mail.gmail.com>
Subject: Re: Week to date function
To: Ireneusz Pluta <ipluta@wp.pl>
Cc: pgsql-sql@postgresql.org
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> CREATE OR REPLACE FUNCTION your_week2date(double precision, double
> precision) RETURNS SETOF date
> AS
> $_$
> SELECT =A0day
> FROM (
> =A0 SELECT =A0(
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 date_trunc('week', ($1::text||'-01-01')::date=
)
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 + ($2::text||' week')::interval
> =A0 =A0 =A0 =A0 =A0 =A0 =A0 + ( d::text||' =A0day')::interval
> =A0 =A0 =A0 =A0 =A0 )::date =A0AS =A0day
> =A0 FROM =A0 =A0generate_series(0, 6) AS d
> ) =A0 alias
> WHERE =A0 to_char(day, 'IYYY')::integer =3D $1
> ORDER
> BY =A0 =A0 =A01
> $_$
> LANGUAGE SQL
> IMMUTABLE

I think it is better to use date_part('year', day) instead of
to_char(...). And may be it is worth to do raise exception when
incorrect week specified.

--=20
Sergey Konoplev

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