Re: Date, Darwen, Pascal and the alternative to Nulls in the RM

I have also been making my way through Date's books. I'm afraid some
basic concepts still elude me. Any way, I have been also trying to
read some logic books to get a deeper feel for RM. Isn't following a
solution to the null problem:

Consider a relation (relvar?):
[social security number, name, age, grade]
(where soc number is the primary key).
Isn't this exactly the same (in logical terms) as:
[soc number, name]
[soc number, age]
[soc number, grade]
The primary key can't be a null. name, age and grade may be safely
'null' (they simply don't exist) in the second representation. The
user may still see the first representation (perhaps views?), and if
he/she enters a null for one of the non-primary-key fields, the actual
logical model simply doesn't 'insert' the null value into its relevant
table (eh...relvar).

I've avoided using the term normalization because I'm even less sure of
its meaning then other stuff I've written.

Does this make any sense?

.

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