X-Received: by 10.67.11.5 with SMTP id ee5mr17331443pad.12.1422886452745; Mon, 02 Feb 2015 06:14:12 -0800 (PST) X-Received: by 10.50.79.170 with SMTP id k10mr138731igx.5.1422886452615; Mon, 02 Feb 2015 06:14:12 -0800 (PST) Path: news.cambrium.nl!textnews.cambrium.nl!feeder1.cambriumusenet.nl!82.197.223.108.MISMATCH!feeder2.cambriumusenet.nl!feeder3.cambriumusenet.nl!feed.tweaknews.nl!81.171.88.16.MISMATCH!hq-usenetpeers.eweka.nl!hq-usenetpeers.eweka.nl!news.glorb.com!hl2no7568796igb.0!news-out.google.com!qk8ni19782igc.0!nntp.google.com!hl2no5670898igb.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.databases.theory Date: Mon, 2 Feb 2015 06:14:12 -0800 (PST) In-Reply-To: <29bc5e77-a12a-430d-bf09-fa966f8d63d0@googlegroups.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=101.175.1.237; posting-account=bFMNewoAAAAHC6b_JPlV7XvI31zIuG5T NNTP-Posting-Host: 101.175.1.237 References: <29bc5e77-a12a-430d-bf09-fa966f8d63d0@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <7c3de54e-cf64-4695-8255-453f880fc882@googlegroups.com> Subject: Re: Hierarchical Model and its Relevance in the Relational Model From: Derek Asirvadem Injection-Date: Mon, 02 Feb 2015 14:14:12 +0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable X-Received-Bytes: 3702 X-Received-Body-CRC: 1546567561 Xref: news.cambrium.nl > On Monday, 2 February 2015 22:46:19 UTC+11, Derek Asirvadem wrote: > My practised opinion is, after 39 years in the industry, 36 in databases,= 30 years pure Relational, is that all data in a database, is related, to a= ll data, in that database. Obviously, not limited to "by referential const= raint", related in various ways. At the very least, it is all related simp= ly because the database is an recovery unit. One step up from that, that y= ou will understand, is the referential constraint, so that is the limit for= you guys. Codd taught me that their are myriad other relations, and apply= ing the RM, I implement some of them. But that is about thirty years ahead= of you guys, and I will not try to explain any of it here. We are stilt, = heh heh, arguing about what a relation is, and whether hierarchies are part= of the RM.=20 In case it needs to be said, I do not mean "Codd taught me" literally, in p= erson. I mean through his papers and articles, through the RM. The more I= applied the RM, the more I understood it, that is applied more than I prev= iously thought. So I applied it more the next time, and in doing so, I lea= rned that it applied in even more ways. In that sense, Codd is still very much alive, much like my dead father is a= live to me internally. His work is a living work, if you interact with it = and respect as the Commandments for Relational Databases, you get way more = out of it than if you argued and fought. That might take you ten or twenty= years of incorrect implementations, as some of you have mentioned. Genuin= e disciples of Codd never had that problem. Of course I implement 100% of all data controls in the db, using RDBMS faci= lities, declaratively. But there is much more to data integrity than that.= There is a whole level of what I call Logical Integrity. To portray tha= t, to document that, I use a set of diagrams, separate to, and entirely bou= nd to, the full IDEF1X data model. Only because IDEF1X doesn't have it. I= DEF1X is not like UML, where everyone and his dog has a different set of sy= mbols and notations, so I don't interfere with it, I don't add symbols, I a= dd a separate diagram. But that is beyond the scope of this thread. I just wanted to clarify the = "Codd taught me" statement, in case someone took that literally.