> I'm still confused on what associations have responsibility for
> holding the keys in their own tables and what ones depend on other
> tables.  Is this right?
>
> Association               Responsibility
> -----------               --------------
> has_one                   foreign
> has_many                  foreign
> belongs_to                local
> has_and_belongs_to_many   foreign (in separate table)
>
> So basically, anything with belongs_to should have the key of the
> thing it belongs to in its table.  All other associations don't.
> Right?  Have I missed any associations?

No, spot on. That's actually a great idea. Let me paste that right into 
the Active Record documentation.

> Also, in the examples I see some occurrences of "belong_to".  Is this 
> a typo?

Yes.

BTW, to the rest of ruby-talk: Is the Rails chatter getting too heavy? 
Should we rather start a new external mailing list? I've been somewhat 
against that in order to get the wikis in use, but it could seem that a 
mailing list is just good for other stuff. Thoughts?
--
David Heinemeier Hansson,
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http://www.loudthinking.com/ -- Broadcasting Brain
http://www.nextangle.com/    -- Development & Consulting Services