What's wrong with nullable columns in composite primary keys?

Question

ORACLE does not permit NULL values in any of the columns that comprise a primary key. It appears that the same is true of most other \"enterprise-level\" systems.

At

Answer 1

I still believe this is a fundamental / functional flaw brought about by a technicality. If you have an optional field by which you can identify a customer you now have to hack a dummy value into it, just because NULL != NULL, not particularly elegant yet it is an "industry standard"