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
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