topmind wrote:
> Nulls are a vendor-specific idea, not inherent to relational.
While I agree with much of your post, nulls now appear to me to be
essential to the relational model (whatever their rights and wrongs).
If one fully normalizes a database then it is likely a join will
require the use of null to pad the resulting virtual relation. Just
because these relations are not persisted on disk, makes them no less
'relations' in the sense of Codd's algebra. As such i am currently
struggling with how one can be against nulls (as per Date's perfectly
justified view) but pro-RM from a completely theoretical standpoint.
