moebooru/db/migrate/025_add_updater_id_to_artists.rb

class AddUpdaterIdToArtists < ActiveRecord::Migration[5.1]
  def self.up
    execute "ALTER TABLE artists ADD COLUMN updater_id INTEGER REFERENCES users ON DELETE SET NULL"
  end

  def self.down
    execute "ALTER TABLE artists DROP COLUMN updater_id"
  end
end