Re: A new proof of the superiority of set oriented approaches: numerical/time serie linear interpolation
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 02 May 2007 14:25:10 -0300
Message-ID: <4638c946$0$4042$9a566e8b_at_news.aliant.net>
>>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.
Date: Wed, 02 May 2007 14:25:10 -0300
Message-ID: <4638c946$0$4042$9a566e8b_at_news.aliant.net>
> Cimode <cimode_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.
If one accepts the idea of relation valued attributes, then one could look at the dbms as a single tuple with a 0-ary candidate key and an RVA for each relvar. Received on Wed May 02 2007 - 19:25:10 CEST