Why does it kill you? A NULL in a row is semantically identical to the row never existing in the first place, unless there is some other non-null column (the pr

Why does it kill you? A NULL in a row is semantically identical to the row never existing in the first place, unless there is some other non-null column (the primary key) that lets you disambiguate between the two cases. It's hardly a problem in practice because all good tables should have primary keys.