doc/technical/archived_migrations/20171012161558_apply_round.rb
class ApplyRound < ActiveRecord::Migration[5.1]
def change
challenges = Challenge.all
challenges.each do |c|
challenge_round = c.challenge_rounds.first
execute "update submissions set challenge_round_id = #{challenge_round.id} where challenge_id = #{c.id};"
end
end
end