A Rails 2.0.2 application configures SQLite3 database by default. This requires you to have SQLlite3 database running and also have the corresponding database adapter installed. Even this is part of the Leopard (Mac OS 10.5+) development kit but this needs extra configuration on non-Leopard machines.

One of the guiding principles of Rails is Convention-over-Configuration. So there are couple of ways you can override this default:

1. Generate the Rails app by specifying the database of your choice. So if you want to use MySQL as the default database, then generate the application as:
   
   jruby -S rails -d mysql myapp
   
   This is assuming you are using JRuby for generating your Rails application.
2. If you want to use Rails without a database, remove ActiveRecord framework by editing "config/environment.rb" and adding the line:
   
   config.frameworks -= [ :active_record ]
   
   Alternatively you can uncomment line 21 in "environment.rb" and remove other frameworks from inside the parentheses.

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