Re: So what's null then if it's not nothing?

JOG schrieb:
> Alexandr Savinov wrote:
>

>>What people cannot understand is that we cannot simply disable nulls. It
>>is too simplistic point of view. It is not possible to say that we will
>>not use nulls and that is all. Why? Because the notion of absence exists
>>in almost any data model. We need to know if an object exists or not. If
>>yes, then we get some value. If not then we get null.

> ears. If you don't know something why try to type it in as a fact
> (outside some logistical efficiency considerations)?.

Because sometimes we have a slot for that and we must write some value into it.

> "We need to know
> if an object exists or not.." - in that case directly _encode_ the fact
> as to whether the said object exists or not, as you would anything

Precisely what I do - directly write null if an object does not exist along this dimension. If it does exist then we write a normal value.

> else. Yes the notion of absence is extremely important, but it is
> absolutely no different to the notion of colour, size, shape, or indeed
> any property. Why the desire to treat it any differently?

Yes, in some models there is no difference.

However, these things are completely different. Because there are two parts of data modeling:

• entity modeling, and
• identitiy mdoeling

They are completely different although exist together. When we are talking about existence then it is about identity modeling. When we are talking about properties (solour, size etc.) then it is all about entity modeling.

Ok, it is not RM but I think this thread did not mention RM so we are talking about data modeling rather than what RM says about that (although RM does not have one concrete opinion about this problem although here I can be wrong).

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