class Participation < ActiveRecord::Base; end class PersonalProfile < ActiveRecord::Base; end class CreateParticipationRecords < ActiveRecord::Migration[4.2] def up event_to_speaker_profiles = execute 'SELECT * FROM events_speaker_profiles' event_to_speaker_profiles.each do |event_to_speaker_profile| profile = PersonalProfile.find_by(id: event_to_speaker_profile['speaker_profile_id']) next if not profile Participation.create! event_id: event_to_speaker_profile['event_id'], participant_id: profile.user_id, approved: true end end def down Participation.destroy_all end end