From: Mario Weilguni <mweilguni@sime.com>
To: pgsql-general@postgresql.org
Subject: Re: Drop NOT NULL constraint !!!
Date: Thu, 21 Nov 2002 07:53:20 +0100
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avpresult: 0, ok, ok

Am Mittwoch, 20. November 2002 20:09 schrieb RenX SalomXo:
>  Does anybody could tell me how to drop a constraint on a column where no
> name was provided to the constraint? How does Pg name constraints?
>
> Thanks

did you add a "CHECK" constraint, or did you use "NOT NULL" in the table definition? For the not null case it's easy:

update pg_attribute 
      set attnotnull=false
where attname='yourattributename'
   and attrelid=(select oid from pg_class where relname='mytable' and relkind='r');

If you added a check constraint, you have to remove the corresponding row from pg_relcheck
and decrement the attribute "relchecks" in pg_class for the table, but I won't do it without having 
a backup at hand.

Backup your data first.

Regards,
	Mario Weilguni