database identifier

In a database the items are often identified by a number or other form of identifier such as a GUID which has no strong meaning in itself, but can be used to refer to the item uniquely in other database records or external references such as a URI. In some databases the items are identified by one or more field values, known as the database 'key'; however, this may be fragile, for example if the combination of name and address is used to identify soemone, but they subsequently move.