Re: Self-referential records

Ovid wrote on 24.01.2010 14:43:
> Assuming I have the following table:
>
>      CREATE TABLE refers (
>        id        SERIAL  PRIMARY KEY,
>        name      VARCHAR(255) NOT NULL,
>        parent_id INTEGER NOT NULL,
>        FOREIGN KEY (parent_id) REFERENCES refers(id)
>    );
> I need to insert two records so that "select * from refers" looks like this:
>
>      =# select * from refers;
>       id | name | parent_id
>      ----+------+-----------
>        1 | xxxx |         1
>        2 | yyy  |         2
>
> The first record can't be inserted because I don't yet know the parent_id.

I ususally identify the root record by setting the parent_id to NULL.
In my experience creating a cycle in the tree creates a lot of trouble that is hard to come by.

Thomas