Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation

On 2 mai, 18:07, Gene Wirchenko <g..._at_ocis.net> wrote:
> Cimode <cim..._at_hotmail.com> wrote:
> >On May 2, 11:18 am, Jon Heggland <jon.heggl..._at_idi.ntnu.no> wrote:
> >> Brian Selzer wrote:
> >> > "Cimode" <cim..._at_hotmail.com> wrote in message
> >> >news:1178044184.315215.167590_at_p77g2000hsh.googlegroups.com...
> >> >> What is a *database value* ? What do you mean that a database
> >> >> (collection of facts) is one single value? Do you mean a relation
> >> >> value? (the database being perceived as one single complex relation?)
>
> >> > The term "database" is pretty loaded. Most of the time a database is a
> >> > value, a set of relations conforming to a particular schema--a
> >> > representation of a collection of facts at a particular instant. In the
> >> > context of modification, on the other hand, a database is a mutable entity
> >> > whose state transitions from value to value as a result of a series of
> >> > events. I use the phrases "database value" and "database state" to
> >> > forestall any confusion.
>
> >> > A set is a value. A database (in the first sense) is a set of named sets
> >> > (relations) of sets (tuples) of named values (attribute values) that
> >> > conforms to a particular schema. Therefore it is a single value.
>
> >> Or, if you want to simplify the above by avoiding "state" and "mutable",
> >> you could say (as D&D do) that a database is a variable---a
> >> dbvar---which has a db value. Which is a tuple.
> >Stating that a database is a relation is much safer.
>
> But likely inaccurate. It may (and probably will) consist of more
> than one relation.
Indeed. I tend to think that a perfectly normalized database is necessarily a single relation. As soon as it is undernormalized, it becomes several relations. Received on Wed May 02 2007 - 20:25:51 CEST