[Dbix-class] table referencing itself

Oliver Gorwits oliver.gorwits at oucs.ox.ac.uk
Wed Dec 20 21:27:29 GMT 2006

Daniel McBrearty wrote:
> CREATE TABLE whatever (
> whatever_id INTEGER NOT NULL REFERENCES whatever(id),
> Is there a way to get the id of the object being created in the
> statement doing the creation? I don't even know if the db (postgresql)
> can do that ... ?

id SERIAL makes the col base itself on a (probably auto-generated) 
sequence. you can just ask the sequence for the next integer, and use 
that in the create.

sequences keep issuing integers, never repeat themselves, and are 
independent of the cols based upon them (so you can do things like get 
the next seq id, then abort a transaction and rollback, but the next 
issued id will still be after that last issued, but aborted, one).

to find the sequence name go to the psql shell and type \d <return> and 
\d whatever <return> (for table "whatever").

not sure what magic DBIC has to aid the above, but I wouldn't be 
surprised if something was in there somewhere to help you :)

Oliver Gorwits, Network Infrastructure Group,
Oxford University Computing Services

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