Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]

From: Paul <paul_at_test.com>
Date: Tue, 07 Jun 2005 10:41:40 +0100
Message-ID: <42a56bd5$0$41904$ed2619ec@ptn-nntp-reader03.plus.net>

Alexandr Savinov wrote:
> For example, what is the difference between row, record, tuple and
> object? They designate one and the same but in different contexts in
> order to emphasize different aspects of the theory where they are used.

Maybe row, record and tuple are all used to describe the same thing, but object is different I think. Rows are identified by their contents alone, but two objects can have identical contents but be different.

I think this is what Date & Darwen describe as the "first great blunder" in one of their publications - the idea that class=table and row=object. They argue that it should be domain=class

Although SQL confuses the issue by allowing tables without candidate keys, and thus duplicate rows, although you still can't uniquely identify them.

Paul. Received on Tue Jun 07 2005 - 04:41:40 CDT