[web2py] table without id

[Cory Coager]

I have created some database tables externally to web2py.  Does web2py
require an id field for tables?  The reason why I'm asking is, when I
use the DAL to do an insert, web2py tries to retrieve the currval of
the insert.  Seeing how I don't have an id, this throws an exception.
How should I handle this?