Path: text.usenetserver.com!out01b.usenetserver.com!news.usenetserver.com!in02.usenetserver.com!news.usenetserver.com!cycny01.gnilink.net!spamkiller2.gnilink.net!gnilink.net!trndny07.POSTED!3abab865!not-for-mail From: "David Cressey" Newsgroups: comp.databases.theory References: Subject: Re: NULLs: theoretical problems? Lines: 19 X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1478 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1478 Message-ID: Date: Wed, 08 Aug 2007 17:19:38 GMT NNTP-Posting-Host: 72.79.236.80 X-Complaints-To: abuse@verizon.net X-Trace: trndny07 1186593578 72.79.236.80 (Wed, 08 Aug 2007 13:19:38 EDT) NNTP-Posting-Date: Wed, 08 Aug 2007 13:19:38 EDT Xref: usenetserver.com comp.databases.theory:166143 X-Received-Date: Wed, 08 Aug 2007 13:19:43 EDT (text.usenetserver.com) "sinister" wrote in message news:wa-dnYfs8-TuAyTbnZ2dnUVZ_tSknZ2d@comcast.com... > 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. > > "Nothin' ain't worth nothin', but it's free." --Kris Kristofferson --