Path: news.f.de.plusline.net!news-fra1.dfn.de!newsfeed.hanau.net!news.tiscali.de!uio.no!ntnu.no!not-for-mail From: Jon Heggland Newsgroups: comp.databases.theory Subject: Re: more closed-world chatter Date: Sat, 05 May 2007 17:50:25 +0200 Organization: Norwegian university of science and technology Lines: 21 Message-ID: References: <4639315f$0$4019$9a566e8b@news.aliant.net> NNTP-Posting-Host: coleburn.idi.ntnu.no Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: orkan.itea.ntnu.no 1178380331 26496 129.241.111.99 (5 May 2007 15:52:11 GMT) X-Complaints-To: usenet@itea.ntnu.no NNTP-Posting-Date: Sat, 5 May 2007 15:52:11 +0000 (UTC) User-Agent: Thunderbird 1.5.0.10 (Windows/20070221) In-Reply-To: Xref: news.f.de.plusline.net comp.databases.theory:43790 paul c wrote: > (Aside - it appears to me that you and Bob B are more or less on the > "same page" I think so. > when it comes to the advantage of sub-typing in dealing with > my question. I don't know about "advantage"; I just don't see how you can avoid it. > Also, for some reason I can't explain very well, I seem to > view types or domains in a very mechanical way meaning that if a user > can define a type that user could also re-define a type which might > invalidate all of an existing db's "propositions". Sounds perfectly reasonable. Isn't this just (like) the user changing any constraint on a database? It might conflict with existing data (and I would suggest the modification in that case be rejected). -- Jon