Re: MV Keys

"Jon Heggland" <heggland_at_idi.ntnu.no> wrote in message news:MPG.1e7138dbe026bb23989778_at_news.ntnu.no...
> In article <iJDNf.676$ZL1.483_at_trndny09>, dcressey_at_verizon.net says...
> > Is a"tuple valued attribute" the same thing as a "relation valued
> > attribute, constrained to a cardinality of one"?
>
> Is a character the same thing as a string, constrained to a length of 1?
> Is any kind of value the same thing as a constrained vector of such
> values? Is a vector a constrained matrix? Why do you ask?

My question was mostly rhetorical. But I was prepared to read, with surprise, an affirmative answer.

To me a relation that only contains one tuple, and the tuple that it contains are different things.

But a salient feature of the MV model seems to be (if I get it right), that we can write out a buch or data
into a Pick file treating some field (like "Major" for a student) as containing only one value, and then, at a later point in time, add multiple majors in the same field, turning the field into a list container. This is odd.

And, again if I read it right, this can be done without breaking anything. That makes me curious. All the rest of Pick files, as far as shown in here, recapitulate things I've dealt with before. Received on Fri Mar 03 2006 - 21:43:21 CET