run

# File activerecord/lib/active_record/migration.rb, line 675
    def run
      target = migrations.detect { |m| m.version == @target_version }
      raise UnknownMigrationVersionError.new(@target_version) if target.nil?
      unless (up? && migrated.include?(target.version.to_i)) || (down? && !migrated.include?(target.version.to_i))
        target.migrate(@direction)
        record_version_state_after_migrating(target.version)
      end
    end