1. Get the Ruby OCI8 driver.  Download the file that ends with “mswin32.rb” and install like this:

   E:\ruby>ruby ruby-oci8-1.0.3-mswin32.rb
   Copy OCI8.rb to e:/ruby/lib/ruby/site_ruby/1.8/DBD/OCI8
   Copy oci8.rb to e:/ruby/lib/ruby/site_ruby/1.8
   Copy oci8lib.so to e:/ruby/lib/ruby/site_ruby/1.8/i386-msvcrt
   OK?
   Enter Yes/No: Yes
   Copying OCI8.rb to e:/ruby/lib/ruby/site_ruby/1.8/DBD/OCI8 ... done
   Copying oci8.rb to e:/ruby/lib/ruby/site_ruby/1.8 ... done
   Copying oci8lib.so to e:/ruby/lib/ruby/site_ruby/1.8/i386-msvcrt ... done
   OK

   You can test the driver by running a query using Ruby.

   E:\>ruby -r oci8 -e "OCI8.new('foo','12345','sid').exec(
   'SELECT * from users') do |r| puts r.join(' | ') ; end"

2. Install the ActiveRecord Oracle adapter.gem

   E:\ruby>install activerecord-oracle-adapter --source http://gems.rubyonrails.org

3. Update config/database.yml to connect to Oracle

   development:
     adapter: oracle
     database: sid
     username: foo
     password: 12345
     timeout: 5000

4. Test by doing a rake db:migrate.
5. Test by running the Ruby on Rails server and making sure there are no errors upon startup.

This article is based on these articles.

• Oracle in Ruby on Rails
• Ruby on Rails with Oracle FAQ
• Connecting Ruby on Rails to Oracle on an Intel Mac in Leopard (Mac OSX 10.5)