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@gmail.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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