nairobi/db/migrate/20170914154743_fix_password_changed_at_default.rb

class FixPasswordChangedAtDefault < ActiveRecord::Migration
  def up
    change_column_default :users, :password_changed_at, Time.new(2015, 1, 1,  1,  1,  1)
  end

  def down
    change_column_default :users, :password_changed_at, Time.now
  end

end