Action controller: Exception Caught while trying to acces recently generated controller on empty Ruby on Rails project

I am new to ruby on rails, just trying to follow some tutorials.I just entered:

rails generate controller helloWorld index

then i started rails server and tried to access http://localhost:3000/hello_world/index and got

Action controller: Exception Caught 

Active开发者_C百科Record::ConnectionNotEstablished

ActiveRecord::ConnectionNotEstablished

in the browser

Did you run rake db:create db:migrate before starting the server.

If you did, pls check your database configuration in config/database.yml. If you can't figure it out, please let us know the contents of that file.