If you're trying to use jruby on rails, and you see an error like this:

GEM_HOME=~/.jrubygem jruby -S rake db:create:all

(in /private/tmp/fnord)

!!! The bundled mysql.rb driver has been removed from Rails 2.2. Please install the mysql gem and try again: gem install mysql.

rake aborted!

no such file to load -- mysql

(See full trace by running task with --trace)

The solution is to run script/generate jdbc:

GEM_HOME=~/.jrubygem jruby -S script/generate jdbc

      exists  config/initializers

      create  config/initializers/jdbc.rb

      exists  lib/tasks

      create  lib/tasks/jdbc.rake

See Nick Sieger's blog for more detail.