-Finally, if the secondary keys are unique, each list will have a length of one, and a separate linked list will
exist for every record in the database. Because this situation is unworkable, linked lists cannot be used
for unique keys. For example, suppose that the CUSTOMER records contain another unique field, say,
Social Security Number. If we attempt to represent this unique secondary key using a linked list, every
Social Security Number will be a separate linked list. Furthermore, each linked list will have just one item
in it: the single record having the indicated Social Security Number.