sqlite with activerecord outside rails

gistfile1.rb

require 'active_record'

ActiveRecord::Base.logger = Logger.new(STDERR)
ActiveRecord::Base.colorize_logging = false

ActiveRecord::Base.establish_connection(
    :adapter => "sqlite3",
    :dbfile  => ":memory:"
)

ActiveRecord::Schema.define do
    create_table :albums do |table|
        table.column :title, :string
        table.column :performer, :string
    end

    create_table :tracks do |table|
        table.column :album_id, :integer
        table.column :track_number, :integer
        table.column :title, :string
    end
end

class Album < ActiveRecord::Base
    has_many :tracks
end

class Track < ActiveRecord::Base
    belongs_to :album
end

album = Album.create(:title => 'Black and Blue',
    :performer => 'The Rolling Stones')
album.tracks.create(:track_number => 1, :title => 'Hot Stuff')
album.tracks.create(:track_number => 2, :title => 'Hand Of Fate')
album.tracks.create(:track_number => 3, :title => 'Cherry Oh Baby ')
album.tracks.create(:track_number => 4, :title => 'Memory Motel ')
album.tracks.create(:track_number => 5, :title => 'Hey Negrita')
album.tracks.create(:track_number => 6, :title => 'Fool To Cry')
album.tracks.create(:track_number => 7, :title => 'Crazy Mama')
album.tracks.create(:track_number => 8,
    :title => 'Melody (Inspiration By Billy Preston)')

album = Album.create(:title => 'Sticky Fingers',
    :performer => 'The Rolling Stones')
album.tracks.create(:track_number => 1, :title => 'Brown Sugar')
album.tracks.create(:track_number => 2, :title => 'Sway')
album.tracks.create(:track_number => 3, :title => 'Wild Horses')
album.tracks.create(:track_number => 4,
    :title => 'Can\'t You Hear Me Knocking')
album.tracks.create(:track_number => 5, :title => 'You Gotta Move')
album.tracks.create(:track_number => 6, :title => 'Bitch')
album.tracks.create(:track_number => 7, :title => 'I Got The Blues')
album.tracks.create(:track_number => 8, :title => 'Sister Morphine')
album.tracks.create(:track_number => 9, :title => 'Dead Flowers')
album.tracks.create(:track_number => 10, :title => 'Moonlight Mile')

puts Album.find(1).tracks.length
puts Album.find(2).tracks.length

puts Album.find_by_title('Sticky Fingers').title
puts Track.find_by_title('Fool To Cry').album_id

very nice. You could change the last lines to:

Album.find_by_title('Sticky Fingers').tracks.each do |t|
  puts "#{t.title}"
end
puts Track.find_by_title('Fool To Cry').album.title