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
