Join Tables between db

I have a site with 2 databases (same server)

1.       Being resources_db (data that never changes, Country, States, various selects and options to select from throughout the site)

2.       default_db users, profiles, things that can be changed, edited by users.

 

Now join tables happen to cross between resources_db and default_db where does the join tables go in these situations? How do you tell Cake where to look?

 

Thanks,

 

Dave