retrospring/db/migrate/20150721154255_add_confirmable_to_devise.rb

class AddConfirmableToDevise < ActiveRecord::Migration[4.2]
  def up
    add_column :users, :confirmation_token, :string
    add_column :users, :confirmed_at, :datetime
    add_column :users, :confirmation_sent_at, :datetime
    add_column :users, :unconfirmed_email, :string
    add_index :users, :confirmation_token, unique: true
    execute("UPDATE users SET confirmed_at = NOW()")
  end

  def down
    remove_columns :users, :confirmation_token, :confirmed_at, :confirmation_sent_at
    remove_columns :users, :unconfirmed_email
  end
end