Re: Relational Inheritance Thoughts

Trent Shipley wrote:
> At the risk of belaboring the point, relational single inheritance resembles
> a hierarchical database, like a traditional computer file system.  A
> relational multiple inheritance database resembles a network database, like
> the once promising CODASYL standard or the GROVE or DOM representation of an
> XML hyper-document.

> A database with relational multiple inheritance is a hybrid between a
> relational database and network database that ought to support any mixture of
> the data models without prejudice.

I'm not sure any of this is true. Relational inheritance (where one
table "inherits" the attributes of another) is a syntactic shorthand,
nothing more. You could re-implement it either with one "master" table
and several "detail" tables or unions of several tables with shared
attribute-names.

In a network-database or document, such as an XML document you use the
hierarchy / network edges to navigate to individual data items, not to
"navigate" (and I don't think the term is correct here) your schema
definition.

--
   Richard Huxton
   Archonet Ltd