Number one rule to updating fields of database rows via Rails migration is to first check if they are existing

migration_update_attributes

class UpdateAddressOfASchool < ActiveRecord::Migration
  def up
    ['Ateneo', 'UP'].each do |name|
      school = School.where(name: name).first
      if school
        school.update_attributes(address: "Quezon City")
      end
    end
  end
end