Re: Use of the term "hierarchy"

Marshall Spight wrote:

> Kenneth Downs wrote:
>> Generally speaking, we seem to use the word hierarchy to mean a situation
>> where a table has a foreign key to itself (or a child table has two
>> foreign keys to the same table that are non-transitive), with the usual
>> assumption that nesting could go to any level and that the levels are
>> indistinguishable from each other.
>>
>> We don't tend to say hierarchy when referring to the structure of related
>> tables, such as Jobs -> Orders -> Order Lines. This always looked like a
>> hierarchy to me though. It is a hierarchy of unlike items, in which the
>> allowed relationships of parent/child are determined by table structure.
>>
>> So if we have hierarchies of unlike items and then those of like items,
>> it seems we may mistake one for the other.
>
> Sure. We've been discussing this a lot. There was even a thread
> I started about a month ago called (IIRC) Three Kinds of Logical Trees.
>
>
http://groups.google.com/group/comp.databases.theory/browse_thread/thread/4278824e341371c5/c10c7a30c510531d
>
> Since then, I've been referring to these as homogeneous trees, and
> static heterogeneous trees. There are also dynamic heterogeneous trees,
> like parse trees.
>
>
> Marshall

I did not catch in that thread the specific example i gave of the employees. Should I reread the thread?

-- 
Kenneth Downs
Secure Data Software, Inc.
(Ken)nneth_at_(Sec)ure(Dat)a(.com)