run

# File activerecord/lib/active_record/migration.rb, line 962
    def run
      migration = migrations.detect { |m| m.version == @target_version }
      raise UnknownMigrationVersionError.new(@target_version) if migration.nil?
      unless (up? && migrated.include?(migration.version.to_i)) || (down? && !migrated.include?(migration.version.to_i))
        begin
          execute_migration_in_transaction(migration, @direction)
        rescue => e
          canceled_msg = use_transaction?(migration) ? ", this migration was canceled" : ""
          raise StandardError, "An error has occurred#{canceled_msg}:\n\n#{e}", e.backtrace
        end
      end
    end