Dennis Lee Bieber <wlfr...@ix.netcom.com> writes: > On Fri, 08 Nov 2013 13:31:02 +0000, Mark Lawrence <breamore...@yahoo.co.uk> > declaimed the following: > > >The only relational database that has no relationships as effectively > >there's only one table, despite what Denis McMahon (amongst others?) > >has said.
Relational databases aren't about implementing relationships between tables. They're about implementing the relational data model <URL:http://www.c2.com/cgi/wiki?RelationalModel> <URL:http://www.c2.com/cgi/wiki?RelationalDatabase>. > In terms of relational database theory -- "relation" IS what > most people call a "table": the dependent data is "related" to the > primary key of the table. Yes. In databases using SQL, one table implements a relation, where “relation” is a term of art from relational data theory. > Foreign keys to other tables are part of the definition. And between two relations connected by a foreign key, there exists a relationship — which is *not* what the “relational” in relational databases are about. Confusing? Yep. Relational theory is *not* a theory about relationship between tables. Relational databases are so called not because of relationships between tables, but because they implement relational theory. -- \ “It is the integrity of each individual human that is in final | `\ examination. On personal integrity hangs humanity's fate.” | _o__) —Richard Buckminster Fuller, _Critical Path_, 1981 | Ben Finney -- https://mail.python.org/mailman/listinfo/python-list
