On Tue, 30 Jul 2002, Jeff Davis wrote:
> Can you point me (someone without a real understanding of relational theory)
> to some good resources that explain the concepts well?
C. J. Date's _An Introduction to Database Systems, Seventh Edition_ is
a fat tome that will give you an extremely good grasp of relational
theory if you take the time to study it. Even just browsing it is well
worthwhile. It has some discussion of "object-oriented" database systems
as well.
In particular (you'll see the relevance of this below) it has an
excellent analysis of the updatability of views.
Date and Darwen's _Foundation for Future Database Systems: the
Third Manifesto_ goes into much more detail about how they feel
object-oriented stuff should happen in relational databases. Appendix E
("Subtables and Supertables") discusses table inheritance. It ends with
this statement:
To sum up: It looks as if the whole business of a subtable inheriting columns from a supertable is nothing but a
syntatic shorthand--not that there is anything wrong with syntatic shorthands in general, of course, but this
particularshorthand does not seem particularly useful, and in any case it is always more than adequately supported
bythe conventional view mechanism.
(This, BTW, addresses the note someone else made here about the
subtable/supertable thing letting him do one insert instead of two
or three; he just needs to create a view and appropriate rules,
and he'll get exactly the same effect. And maybe that will help
fix his index problems, too....)
cjs
--
Curt Sampson <cjs@cynic.net> +81 90 7737 2974 http://www.netbsd.org Don't you know, in this new Dark Age, we're
alllight. --XTC
