From: "peter_douglass" Newsgroups: comp.object References: <3b44a4a2$1@tobjects.newsource.com> <_Xx17.26702$C81.2082162@bgtnsc04-news.ops.worldnet.att.net> Subject: Re: A numerical methods viewpoint on OO/FP/Relational Date: Sat, 7 Jul 2001 14:53:59 -0400 Lines: 18 X-Newsreader: Microsoft Outlook Express 4.72.3110.1 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 NNTP-Posting-Host: 216.41.73.178 Message-ID: <3b47185f@tobjects.newsource.com> X-Trace: tobjects.newsource.com 994515039 216.41.73.178 (7 Jul 2001 15:10:39 +0100) Mikito Harakiri wrote [a distinction between relational and constraint databases]. Might I ask if there is anything in constraint databases which violates the relational model? If so, is this violation of the relational model necessary in order to impose arbitrary constraints on the database? Leaving theory aside for a moment and looking at commercial products, ugliness aside, is it not true that with sufficient effort, one can program any arbitrary constraint on a database? Similarly, ugliness aside, doesn't the Turing completeness of SQL (with recursive queries) imply that any query can be expressed in SQL? --PeterD