Path: news.easynews.com!newsfeed1.easynews.com!easynews.com!easynews!uunet!dfw.uu.net!an02.austin.ibm.com!ausnews.austin.ibm.com!sp15ce20.hursley.ibm.com!not-for-mail From: "Paul Vernon" Newsgroups: comp.databases.theory Subject: Re: View updating in practice? Date: Mon, 11 Nov 2002 12:18:02 -0000 Organization: IBM Hursley Lines: 24 Message-ID: References: NNTP-Posting-Host: dyn-9-140-177-100.warwick.uk.ibm.com X-Trace: sp15at20.hursley.ibm.com 1037017132 19376 9.140.177.100 (11 Nov 2002 12:18:52 GMT) X-Complaints-To: news@hursley.ibm.com NNTP-Posting-Date: Mon, 11 Nov 2002 12:18:52 +0000 (UTC) X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Xref: newsfeed1.easynews.com comp.databases.theory:23533 X-Received-Date: Mon, 11 Nov 2002 05:39:22 MST (news.easynews.com) Jens Lechtenbörger" wrote in message news:m2el9unz6d.fsf@pcwi1068.uni-muenster.de... > > > Personally, I believe that view updates are dangerous in most > > > situations as users cannot understand what is going on. > > > > This is similar to my general feelings to. It is my position that > > unless views are 'information equivalent' to their underlying base > > relvars (which is, I believe is equivalent to taking a constant > > complement), then view updates should simply be seen as a > > shorthand - a way for users to get the DMBS to generate base > > update statements from the users desire of what the value of some > > relational expression looks like. > > The constant complement approach is less restrictive. E.g., under > constant complement you may issue UPDATE statements against > projection views, or INSERT into selection views. Fair enougth. Maybe I should have said an 'information equivalent subset' Regards Paul Vernon Business Intelligence, IBM Global Services