Message-ID: <39044.157.92.152.53.1126634982.squirrel@webmail.fmed.uba.ar>
In-Reply-To: <20050912230323.GA63469@winnie.fuhr.org>
References: <56093.157.92.152.53.1126538482.squirrel@webmail.fmed.uba.ar>
	<20050912230323.GA63469@winnie.fuhr.org>
Date: Tue, 13 Sep 2005 15:09:42 -0300 (ART)
Subject: Re: refer a column as a varible name?
From: gherzig@fmed.uba.ar
To: "Michael Fuhr" <mike@fuhr.org>
Cc: gherzig@fmed.uba.ar, pgsql-sql@postgresql.org
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Im using pg 8.0. I personally dont have problem in using pl/perl, but none
of my companions is a perl programmer, so i guess the IF..THEN seems to be
an easy (altough not preferable) solution.

Thank you very much Michael.

Gerardo
> On Mon, Sep 12, 2005 at 12:21:22PM -0300, gherzig@fmed.uba.ar wrote:
>> suppose the
>>
>> type mycolumn as (field1, varchar, field2 varchar)
>> and
>>
>> field_name = ''field1''
>>
>> and returnValue declared as mycolumn
>> ...
>> can i say returnValue.$field_name = ''ok''?
>
> To achieve this in PL/pgSQL you'll need to use a conditional statement
> (IF field_name = 'field1' THEN ...).  I'm not sure if a solution
> involving EXECUTE is possible; if so then it's probably non-obvious.
>
> What version of PostgreSQL are you using, and do you have a requirement
> to use PL/pgSQL?  In 8.0 PL/Perl can return composite types and such
> an assignment would be trivial:
>
> CREATE TYPE mycolumn AS (field1 varchar, field2 varchar);
>
> CREATE FUNCTION foo(varchar) RETURNS mycolumn AS $$
> my $field_name = $_[0];
> my $returnValue = {$field_name => "ok"};
> return $returnValue;
> $$ LANGUAGE plperl IMMUTABLE STRICT;
>
> SELECT * FROM foo('field1');
>  field1 | field2
> --------+--------
>  ok     |
> (1 row)
>
> SELECT * FROM foo('field2');
>  field1 | field2
> --------+--------
>         | ok
> (1 row)
>
> --
> Michael Fuhr
>
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-- 
Gerardo Herzig
Direccion General de Organizacion y Sistemas
Facultad de Medicina
U.B.A.