create_databases.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'activerecord'

File.unlink('biology_data.db') rescue nil
File.unlink('life_form_data.db') rescue nil

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

ActiveRecord::Schema.define do
  create_table :phyla do |t|
    t.string :name
  end

  insert("insert into phyla(name) values('Acanthocephala')")
  insert("insert into phyla(name) values('Brachiopoda')")
  insert("insert into phyla(name) values('Chaetognatha')")
  
  
  create_table :divisions do | t |
    t.string :name
  end
  
  insert("insert into divisions(name) values('Anthocerotophyta')") 
  insert("insert into divisions(name) values('Bryophyta')") 
  insert("insert into divisions(name) values('Marchantiophyta')") 
  
  create_table :species do | t |
    t.string :name 
    t.integer :phylum_id
    t.integer :division_id
  end
    
end

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

ActiveRecord::Schema.define do
  create_table :life_forms do |t|
    t.string :name
  end

  insert("insert into life_forms(name) values('Polymorphus spp')")
  insert("insert into life_forms(name) values('Syringothyris sp')")
  insert("insert into life_forms(name) values('Spadella cephaloptera')")
  insert("insert into life_forms(name) values('Phaeoceros laevis')")
  insert("insert into life_forms(name) values('Sphagnum moss')")
  insert("insert into life_forms(name) values('Riccia fluitans')")
end

multiple_ar_databases.rb

#!/usr/bin/env ruby 
require 'rubygems'
require 'activerecord' 
require 'spec'

class BiologyData < ActiveRecord::Base
  self.abstract_class = true 
end

class Species < BiologyData
  set_table_name :species
  belongs_to :division
  belongs_to :phylum
end

class Division < BiologyData
  has_many :species
end

class Phylum < BiologyData
  set_table_name :phyla
  has_many :species
end

class LifeForm < ActiveRecord::Base;end
  
describe "MultipleArDatabases" do 
  before(:all) do
    require 'create_databases'
    BiologyData.establish_connection(
      :adapter => 'sqlite3',
      :dbfile => 'biology_data.db'
    )

    LifeForm.establish_connection(
      :adapter => 'sqlite3',
      :dbfile => 'life_form_data.db'
    )
  end
  
  it "should classify life forms into Division or Phylum" do 
    LifeForm.find(:all).each do | life_form | 
      case life_form.name # Simulate code that would actually classify the life form
      when 'Polymorphus spp'
        Species.create!(:name => 'Polymorphus spp', :phylum => Phylum.find_by_name('Acanthocephala'))
      when 'Syringothyris sp'
        Species.create!(:name => 'Syringothyris sp', :phylum => Phylum.find_by_name('Brachiopoda'))
      when 'Spadella cephaloptera'
        Species.create!(:name => 'Spadella cephaloptera', :phylum => Phylum.find_by_name('Chaetognatha'))
      when 'Phaeoceros laevis'
        Species.create!(:name => 'Phaeoceros laevis', :division => Division.find_by_name('Anthocerotophyta'))
      when 'Sphagnum moss'
        Species.create!(:name => 'Sphagnum moss', :division => Division.find_by_name('Bryophyta'))
      when 'Riccia fluitans'
        Species.create!(:name => 'Riccia fluitans', :division => Division.find_by_name('Marchantiophyta'))
      end
    end
    
    puts "\n" * 3

    Phylum.find(:all).each do | phylum |
      phylum.species.each do | species |
        puts "-" * 80 
        puts "Species: #{species.name}, Phylum: #{species.phylum.name}" 
      end
    end
    
    Division.find(:all).each do | division |
      division.species.each do | species |
        puts "-" * 80
        puts "Species: #{species.name}, Division: #{species.division.name}"
      end
    end
  end
end