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root of parent-child table with NOT NULL constraint

From: bill(at)wadley(dot)org
To: pgsql-novice(at)postgresql(dot)org
Subject: root of parent-child table with NOT NULL constraint
Date: 2002-05-02 19:07:21
Message-ID: Pine.LNX.4.43.0205021357500.5681-100000@ensim.rackshack.net (view raw or flat)
Thread:
Lists: pgsql-novice
Hello!

I've created the following table that (I hope) represents groups that
have a relationship to their parent group:

   CREATE TABLE Groups
   (
      Id INTEGER,
      ParentId INTEGER
         CONSTRAINT ParentId_Constraint NOT NULL REFERENCES Groups(Id),
      CONSTRAINT Groups_PK PRIMARY KEY (Id)
   );

The question is: how do I add the first group? The very first group is
the root group, and doesn't have a parent.

My choices seem to be to either:

- create the table without the constraint, add a group that will be the
  parent of all "root" groups, then add the constraint. The problem with
  this solution seems to be that dump and restores will be problematic.

- remove the NOT NULL constraint altogether, but then I won't get the
  kind of referential integerity I want.

So, kind sirs/madams, what am I missing?

Thank you!

Bill Wadley


Responses

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Next:From: Terrence BrannonDate: 2002-05-02 21:09:01
Subject: Re: non-root installation of Postgresql?
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Subject: Re: error messages

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