Path: news.easynews.com!core-easynews!newsfeed1.easynews.com!easynews.com!easynews!news-feed01.roc.ny.frontiernet.net!nntp.frontiernet.net!logbridge.uoregon.edu!newsfeed.stanford.edu!postnews1.google.com!not-for-mail From: neo55592@hotmail.com (Neo) Newsgroups: comp.databases.theory Subject: Re: Do Data Models Need to built on a Mathematical Concept? Date: 4 May 2003 17:06:22 -0700 Organization: http://groups.google.com/ Lines: 12 Message-ID: <4b45d3ad.0305041606.1b1357bc@posting.google.com> References: <17ce58cf.0304240518.34ebfe22@posting.google.com> <4b45d3ad.0305011433.5ae8baa4@posting.google.com> <3EB1AA25.50307@atbusiness.com> <4b45d3ad.0305021419.4226e8b@posting.google.com> <4b45d3ad.0305031919.438d71d2@posting.google.com> NNTP-Posting-Host: 67.98.160.232 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1052093182 31780 127.0.0.1 (5 May 2003 00:06:22 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: 5 May 2003 00:06:22 GMT Xref: core-easynews comp.databases.theory:26156 X-Received-Date: Sun, 04 May 2003 17:05:52 MST (news.easynews.com) > > But, in the rdb model, that flexibility cannot be > > fully realized because the type of values in a domain is restricted to > > some hardware dependent type (ie int, long, date, 50 chars, etc). > > That might be a limitation on, say, Oracle, but it's not a limitation > of the relational model. Domains can be anything; the relational > model doesn't say anything about them at all, other than to say > they are sets of values. You are correct, in the rdb model itself, a tuple's values are not associated with any data type. Data types only appear in implementation of the rdb model.