Re: named generic constraints [feature request]

Hello

do you know domains? It is very similar to your proposal.

http://www.postgresql.org/docs/8.2/static/sql-createdomain.html

Regards
Pavel Stehule

2009/11/23 Caleb Cushing <xenoterracide(at)gmail(dot)com>:
> So last time I checked this wasn't possible (at least not that anyone
> has told me). I'd like to be able to create constraints that aren't
> tied to a specific table/column.
>
> I think that the syntax would look something like this
>
> CREATE CONSTRAINT empty CHECK (VALUE = '\0' );
>
> this should allow us to do thinks like
>
> CREATE TABLE users (
>              username TEXT NOT empty
> );
>

constraint cannot be part of expression.

CREATE OR REPLACE FUNCTION emptystr(text)
RETURNS bool AS $$
SELECT $1 <> ''; -- it is SQL not C
$$ LANGUAGE sql;

CREATE TABLE users(
username TEXT CHECK (NOT emptystr(username)),
...

p.s. Is it related to ANSI SQL?

Regards
Pavel Stehule

> the example from create domain (modified)  is also pretty good
>
> CREATE CONSTRAINT zip CHECK(
>   VALUE ~ '^\\d{5}$'
> OR VALUE ~ '^\\d{5}-\\d{4}$'
> );
>
> --
> Caleb Cushing
>
> http://xenoterracide.blogspot.com
>
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