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Re: Active Record

From: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
To: Emanuel Calvo Franco <postgres(dot)arg(at)gmail(dot)com>
Cc: pgsql-es-ayuda(at)postgresql(dot)org
Subject: Re: Active Record
Date: 2009-03-27 15:01:20
Message-ID: 20090327150119.GQ11993@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-es-ayuda
Emanuel Calvo Franco escribió:

> Alvaro: Se que tiene que haber pero no logro 'joinar' correctamente
> las tablas del catalogo...
> ¿cual es la consulta que trae el nombre del campo que es primary key y su
> tipo? Estuve explorando lo que utiliza psql en sus consultas pero no
> no doy en el clavo,
> que campo linkea pg_constraint y pg_attiributes?

Necesitas pg_index, no pg_constraint.  Prueba así:

select
  pg_attribute.attname,
  format_type(pg_attribute.atttypid, pg_attribute.atttypmod)
from pg_index, pg_class, pg_attribute
where
  pg_class.oid = 'foo'::regclass and
  indrelid = pg_class.oid and
  pg_attribute.attrelid = pg_class.oid and
  pg_attribute.attnum = any(pg_index.indkey);


alvherre=# create table emanuel (calvo int, franco numeric(3, 2), primary key (calvo, franco));
NOTICE:  CREATE TABLE / PRIMARY KEY creará el índice implícito «emanuel_pkey» para la tabla «emanuel»
CREATE TABLE

alvherre=# select 
alvherre-#   pg_attribute.attname, 
alvherre-#   format_type(pg_attribute.atttypid, pg_attribute.atttypmod) 
alvherre-# from pg_index, pg_class, pg_attribute 
alvherre-# where 
alvherre-#   pg_class.oid = 'public.emanuel'::regclass and
alvherre-#   indrelid = pg_class.oid and
alvherre-#   pg_attribute.attrelid = pg_class.oid and 
alvherre-#   pg_attribute.attnum = any(pg_index.indkey);

 attname | format_type  
---------+--------------
 calvo   | integer
 franco  | numeric(3,2)
(2 filas)

-- 
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
"I must say, I am absolutely impressed with what pgsql's implementation of
VALUES allows me to do. It's kind of ridiculous how much "work" goes away in
my code.  Too bad I can't do this at work (Oracle 8/9)."       (Tom Allison)
           http://archives.postgresql.org/pgsql-general/2007-06/msg00016.php

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