Re: Relations as Repeating Groups & Namespaces

From: x <x-false_at_yahoo.com>
Date: Thu, 3 Jun 2004 13:12:10 +0300
Message-ID: <40bef890_at_post.usenet.com>


"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c9m55r$k99$1_at_news.netins.net...
> Namespaces ...
> Think of a DBMS schema by whatever name as determining a namespace.
>
> A relation within that schema is named uniquely within that namespace.
The
> relation is then a sub-namespace where attributes are named uniquely
within
> that namespace.
>
> Within a SQL-RDBMS I could not think of any other clear namespaces below
> that level. There are undesignated namespaces for values, such as a State
> attribute providing a scope for the City attribute so if the value of City
> is "Grand Rapids" that value does not stand on its own, it requires a
> designation, such as a State of MI, to resolve the meaning of the value.
>
> Repeating Groups...
> The root name space (an Oracle schema, for example) has relations as
> entities and, therefore, it has repeating groups (which relations are) as
> entities. The secondary namespaces, relations, are now permitted to have
> repeating groups too, but they are not part of the SQL-92 standard and
> infrequently used by anyone using a SQL-DBMS.
>
> Other models go one or more levels deeper than the relational model in
> permitting namespaces below the relational level. Other models are also
> more consistent in permitting elements within the root name space to be
> repeating groups (e.g. relations) as well as elements within
sub-namespaces
> and so on.
>
> So, if you look at the root name space as analogous to a relation, you can
> see that it would be mathematically elegant, at least, to permit the top
> level name space and sub-name spaces to play by the same rules rather than
> being decidedly different as they are in a SQL-DBMS.
>
> Did that make any sense? If not, ask questions as I want to write this up
> in a way that is not dismissed (or would like to know if this point is so
> stupid it should be dismissed, but be gentle ;-)
> Thanks! --dawn

Hierarchical namespaces tend to be dependent on the applications. Hierarchical namespaces tend to classify *things*. We need a method general enough to deal with any kind of facts. But I agree that "labeling" is one of the human abilities.

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Received on Thu Jun 03 2004 - 12:12:10 CEST

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