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
