Path: text.usenetserver.com!out02b.usenetserver.com!news.usenetserver.com!in04.usenetserver.com!news.usenetserver.com!nx02.iad01.newshosting.com!newshosting.com!post01.iad01!news.aliant.net!not-for-mail Date: Wed, 08 Aug 2007 16:10:34 -0300 From: Bob Badour User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 Newsgroups: comp.databases.theory Subject: Re: NULLs: theoretical problems? References: <46b9b627$0$4048$9a566e8b@news.aliant.net> <1186582837.431878.213670@22g2000hsm.googlegroups.com> <46b9dc62$0$4020$9a566e8b@news.aliant.net> <1186598966.500240.251730@19g2000hsx.googlegroups.com> In-Reply-To: <1186598966.500240.251730@19g2000hsx.googlegroups.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Lines: 45 Message-ID: <46ba14f1$0$4063$9a566e8b@news.aliant.net> NNTP-Posting-Host: 142.176.76.107 X-Complaints-To: abuse@aliant.net Xref: usenetserver.com comp.databases.theory:166146 X-Received-Date: Wed, 08 Aug 2007 15:09:38 EDT (text.usenetserver.com) Jan Hidders wrote: > On 8 aug, 17:09, Bob Badour wrote: > >>Jan Hidders wrote: >> >>>On 8 aug, 14:26, Bob Badour wrote: >> >>>>sinister wrote: >> >>>>>Many discussions point out one deficiency of NULLs: that they collapse >>>>>multiple, distinct concepts into one ("no value possible," "value missing," >>>>>"value not available at this time", etc). >> >>>>>What are the other theoretical problems? My impression from skimming some >>>>>threads in this ng is that some anomalies might occur, maybe having to do >>>>>with NULLs and joins, or NULLs and keys composed of more than one field, but >>>>>I'm not sure. >> >>>>The ultimate theoretical problem is a complete lack of any theory >>>>underpinning NULL. >> >>>Just to avoid any misunderstandings: there has of course been lots of >>>theory on certain interpretations of null values, such as the work by >>>Raymond Reiter and by Joachim Biskup, but not on the specific meaning >>>(if you can call it that) that they were given in SQL. Whether that is >>>necessarily a big problem is IMO not so easy to say. >> >>In other words, some folks accept that NULL exists without any >>theoretical underpinning and then create theories of interpretation. > > Indeed. Because, as we all know, proposing and investigating > alternatives is the same as accepting something's existence. > > >>How >>exactly does that differ from scriptural interpretation and theories >>thereof? > > Exactly! Rejecting straight away null values in any form or shape > without any sort of investigation of their properties would have been > much more scientific. :-) That doesn't answer the question. How does it differ from scriptural interpretation and theories thereof?