Обсуждение: check

how would you go about enforcing the default value:

I have a nextval('seq') as my default and on an insert I don't want any 
other value to be allowed.

forget my last query about inheritance issues

Look at:

http://techdocs.postgresql.org/

Look at the introduction to RULES where they do a read-only column.

Chris

----- Original Message ----- 
From: "Matt" <matthew.berardi@weilpublishing.com>
To: <pgsql-sql@postgresql.org>
Sent: Saturday, June 15, 2002 2:47 AM
Subject: [SQL] check


> how would you go about enforcing the default value:
> 
> I have a nextval('seq') as my default and on an insert I don't want any 
> other value to be allowed.
> 
> forget my last query about inheritance issues
> 
> 
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On Fri, 14 Jun 2002, Matt wrote:

> how would you go about enforcing the default value:
>
> I have a nextval('seq') as my default and on an insert I don't want any
> other value to be allowed.

Don't do a default, do a before trigger that sets the value so that even
if a value is specified it uses the sequence anyway (or you could
potentially check that it's currently null and error I guess as well).

On Fri, 14 Jun 2002 14:47:32 -0400, Matt
<matthew.berardi@weilpublishing.com> wrote:
>how would you go about enforcing the default value:
>
>I have a nextval('seq') as my default and on an insert I don't want any 
>other value to be allowed.

Matt,
   CREATE TABLE tab (id INTEGER NOT NULL DEFAULT 0, ...

and add a before insert trigger that *unconditionally* puts
nextval('seq') into new.id.  I guess, you don't want to allow your
users to change the id of an existing row, so you might also want to
add a before update trigger that sets new.id to old.id.

ServusManfred