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