Re: What does this NULL mean?

dawn wrote:
> Eric Junkermann wrote:
>
>>...
>>
>>The best way to look at a NULL is as a sort of denormalisation. If we
>>have a table X {A, B, C} where A is the key, B is a column we are not
>>currently interested in, and C is the column which is NULL in at least
>>one row, then we are really talking about two tables X1 {A, B} and Y {A,
>>C}, where at least one row in X1 does not have a corresponding row in Y.
>
>
> Within relational theory, I think you are exactly right that it is a
> normaliztion issue and there is no place for nulls in a fully
> normalized model. That is the position I have taken within the context
> of relational theory. Outside of the RM (where I prefer to live), I
> see it differently.
>
>

So nulls are okay in a not-"fully normalized' relation, eg. one in 2NF?

Ignoring the fact that X {A,B,C} seems malformed, ie., inapt, in the first place, wouldn't a more apt comparison be with normalization as opposed to denormalization or maybe better, de-composition?

cheers,
p Received on Sun Dec 11 2005 - 02:23:18 CET