Re: teaching relational basics to people, questions

On Sat, 28 Nov 2009 05:06:40 GMT, paul c <toledobythesea_at_oohay.ac> wrote:

[snip]

>The only thing I wonder about is why constraints must be truth-valued.
>I'd rather they were allowed to have relation values other than dee and
>dum. Seems the only way to allow defaults/mandatory tuples without
>introducing some other concept.

     Is the given constraint true of the data? Either it is, or it is not. That is why constraints are truth-valued.

     What other values could you use? What would having a general relation value as a result tell you about the constraint being followed or not?

Sincerely,

Gene Wirchenko Received on Tue Dec 01 2009 - 03:23:40 CET