Re: On view updating

"Alfredo Novoa" <alfredo_at_ncs.es> skrev i en meddelelse news:e4330f45.0409210312.3b1ec70b_at_posting.google.com...
> "Peter Koch Larsen" <pklspam_at_mailme.dk> wrote in message
news:<Vmb3d.50270$Vf.2438722_at_news000.worldonline.dk>...
>
> > I do not agree. Remove the "AND ONLY IF", and we can talk.
>
> Jan and Hegner say that this is the most common approach.
>
> > Yes - the rules for view updates in the third maniphesto are downright
> > awful.
>
> They are not in the manifesto.

They are on pp 150-151 in the second edition. Just a sketch, really, but enough to tell me something had to be wrong. (Pages are cited from memory - might be wrong)

>
> > Now I do not know what rules you are talking about.
>
> About Date & McGoveran rules.

I'll study these further - i just assumed that they were as described above - using references from other posts.

>
> > A sensible DBMS should
> > have no problem with the above deduction.
>
> But a DBMS that uses that rules can not make the above deduction.

I must look that rule up. ;-)

>
> > Why not read some "real" database theory?
>
> Because it does not solve the problem, and the Date & McGoveran's
> approach only needs some little adjustements to be very useful IMO.
>
> > something about updates of views. You could also check the work of
Stephen
> > Hegner (http://www.cs.umu.se/~hegner/Publications/db.html).
>
> I don't think that I can implement view updates with that.

If you are in the process of implementing your own view update, please keep us informed.... this sounds exciting.

>
>
> Regards

/Peter Received on Tue Sep 21 2004 - 18:27:18 CEST