Re: refer a column as a varible name? - Mailing list pgsql-sql

From gherzig@fmed.uba.ar
Subject Re: refer a column as a varible name?
Date
Msg-id 39044.157.92.152.53.1126634982.squirrel@webmail.fmed.uba.ar
Whole thread Raw
In response to Re: refer a column as a varible name?  (Michael Fuhr <mike@fuhr.org>)
List pgsql-sql
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
>
> ---------------------------(end of broadcast)---------------------------
> TIP 1: if posting/reading through Usenet, please send an appropriate
>        subscribe-nomail command to majordomo@postgresql.org so that your
>        message can get through to the mailing list cleanly
>
>


-- 
Gerardo Herzig
Direccion General de Organizacion y Sistemas
Facultad de Medicina
U.B.A.


pgsql-sql by date:

Previous
From: Marcin Piotr Grondecki
Date:
Subject: Re: SELECT: retrieve only 2 rows next to known row
Next
From: Joost Kraaijeveld
Date:
Subject: What should this query match?