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Message-ID: <b918cf3d050628042253044ba@mail.gmail.com>
Date: Tue, 28 Jun 2005 11:22:36 +0000
From: Mike Rylander <mrylander@gmail.com>
Reply-To: Mike Rylander <mrylander@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: ENUM like data type
In-Reply-To: <11bgc1oblfasq3d@corp.supernews.com>
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References: <11bgc1oblfasq3d@corp.supernews.com>

On 6/21/05, MRB <nomail@example.com> wrote:
> Hi All,
>=20
> I have something in mind I'm not certain is do-able.
>=20
> I'm working with a lot of data from MySQL where the MySQL ENUM type is us=
ed.
>=20

MySQL's ENUM is basically a wrapper for CHECK.  You can use a CHECK
constraint like this:

CREATE TABLE test(
    testfield TEXT CHECK (testfield IN( 'Bits', 'of', 'data'))
);

> This is not a big problem per se but creating the proper lookup tables
> is becoming a bit tedious so I was hoping to make something better of it.
>=20
> Here is where I get uncertain as to if this is possible. My idea is to
> create a pseudo type that triggers the creation of it's lookup tables
> the same way the SERIAL type triggers creation of a sequence and returns
> an int with the right default value.

Although you can't create a generic type to handle this, you can
create a DOMAIN to wrap up your constraint for each "enum" type field
that you want:

CREATE DOMAIN fruit AS TEXT CHECK (VALUE IN ('apple','orange','banana'));
CREATE TABLE eat (
  food fruit
);

http://www.postgresql.org/docs/8.0/interactive/sql-createdomain.html

Hope that helps.

--=20
Mike Rylander
mrylander@gmail.com
GPLS -- PINES Development
Database Developer
http://open-ils.org