SQL to CSV with Rails

csv_from_sql_rails.rb

sql='select event_type as code, country, state, location, name from tracks group by code, country, state, location, name order by code, country, state, location, name;'
pg_res = ActiveRecord::Base.connection.execute(sql)

csv_file = CSV.generate do |csv|
  csv << %w{code country state location name}
  pg_res.values.each { |line| csv << line }
end

File.write('tmp/tracks_export.csv', csv_file)