Uninitialized method 'init' for MySql::Class

I’ve been going through the Ruby on Rails tutorial at OnLamp.com on my
Debian machine, and I ran into the following error after creating a
‘recipes’ table in my ‘cookbook’ database:

NoMethodError in RecipeController#new
uninitialized method ‘init’ for MySql::Class
RAILS_ROOT: /var/rails/cookbook/public/…/config/…

Any ideas on how to fix this? Thanks.