Re: some information about anchor modeling

On Jul 18, 8:21 pm, Eric <e..._at_deptj.eu> wrote:
> On 2012-07-18, vldm10 <vld..._at_yahoo.com> wrote:
>
> > ...
> > 2. Today, more than 90% of databases have an identifier which is a
> > property of the corresponding entity. The VIN ? Vehicle Identification
> > Number is a good example. For these databases the following is true:
> > a) This identifier is much better than the surrogate key.
> > b) These databases do not have any reason to use a surrogate key.
> > ...
>
> The VIN (and most other such things) is nothing more or less than
> Somebody Else's Surrogate Key. It is not an intrinsic property of the
> object it refers to.
>
> Eric
> --
> ms fnd in a lbry

The VIN exists in a database and in the real world.

Each surrogate key only exists in a database. This imply(for example) that the VIN and a surrogate key have very different semantics.

The VIN is an intrinsic property.
A property is an intrinsic property of an entity if we can say: “yes, this entity has this property”. Each attribute i.e. a particular value of a property, we determine by applying identification. For example, an adrress is not an intrinsic property of a person.

Note also that most entities are made by man.( Cars, buildings, credit cards, goods, invoices, etc )

Vladimir Odrljin Received on Thu Jul 19 2012 - 02:48:02 CEST