database.rb

require 'rubygems'
require 'sqlite3'
require 'sequel'

# Adding this monkey-patch makes it work on MacRuby.
module Sequel
  class Dataset
    def single_record
      record = nil
      clone(:limit=>1).each{|r| record = r; return r}
      record
    end
  end
end

DB = Sequel.sqlite()

DB.create_table :entries do
  primary_key :id
  String :words
end

DB[:entries].insert(:words => "Hello MacRuby!")
puts "Querying for all entries records: #{DB[:entries].all.to_s}"
puts "Query for just the first record: #{DB[:entries].first}"
puts "Query for record based on id: #{DB[:entries].where(:id => 1).first.to_s}"

#results

# $ macruby database.rb 
# Querying for all entries records: [{:id=>1, :words=>"Hello MacRuby!"}]
# Query for just the first record: 
# Query for record based on id: 

# $ rvm use 1.9.2
# $ ruby database.rb 
# Querying for all entries records: [{:id=>1, :words=>"Hello MacRuby!"}]
# Query for just the first record: {:id=>1, :words=>"Hello MacRuby"}
# Query for record based on id: {:id=>1, :words=>"Hello MacRuby!"}