Re: Relation Schemata vs. Relation Variables
From: Keith H Duggar <duggar_at_alum.mit.edu>
Date: 20 Aug 2006 17:58:14 -0700
Message-ID: <1156121894.123519.209510_at_74g2000cwt.googlegroups.com>
Date: 20 Aug 2006 17:58:14 -0700
Message-ID: <1156121894.123519.209510_at_74g2000cwt.googlegroups.com>
Brian Selzer wrote:
> For instance, consider the following states for a relation
> describing people's marital status, and a transition
> constraint that says: Single people can't become Divorced:
>
> Current Proposed
> Jane Jones Married Jane Jones Married
> Jane Smith Single Jane Smith Divorced
Please express this constraint using relational calculus. I'm particularly interested to see how "people" and "become" are expressed.
Thank you.
- Keith -- Fraud 6