Don't forget to delete "rake.gemspec"

C:/Ruby192/lib/ruby/1.9.1/rubygems.rb:340:in `bin_path': can't find executable r
ake for rake-0.8.7 (Gem::Exception)
from C:/Ruby192/bin/rake:19:in `<main>'

If you encounter the above error when you enter "rake db:create" command , delete "rake.gemspec" in C:/Ruby192/lib/ruby/1.9.1/gems/specifications or C:\Ruby192\lib\ruby\gems\1.9.1\specifications