Topic: ActiveRecord::ConnectionNotEstablished error

I am new to Ruby on Rails and am going through a tutorial at http://ruby.railstutorial.org/. I am currently working on Chapter 3 static pages section of the tutorial. I continually get ActiveRecord::ConnectionNotEstablished when I try to view pages on my localhost. In the command line I used

Re: ActiveRecord::ConnectionNotEstablished error

Solved. I was using an older pdf version of the tutorial, latest Gemfile is:
source 'https://rubygems.org'

gem 'rails', '3.2.1'

group :development, :test do
  gem 'sqlite3', '1.3.5'
  gem 'rspec-rails', '2.8.1'
end

# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '3.2.3'
  gem 'coffee-rails', '3.2.2'
  gem 'uglifier', '1.2.3'
end

gem 'jquery-rails', '2.0.0'

group :test do
  gem 'capybara', '1.1.2'
end

group :production do
  gem 'pg', '0.12.2'
end