Re: Relation Schemata vs. Relation Variables

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

The schema does not contain enough information to validate marital status.

For instance, if a person switches from single to divorced, do you reject it and have them call you an idiot because they are trying to correct a mistake?

Or, do you put in some absurd requirement that the person change to married, then to divorced?

Why not just record what you know? A table of claimed marital statuses with effective dates would detail the history of the claimed states, recording what you've been told and offering future investigation.

P.S. the Catholic Church solves this problem the old fashioned way, with a single piece of paper per individual. If two people want to get married in parish A, the church secretary at Parish A sends the vital stats off to Church B, the groom's baptism church, and Church C, the bride's baptism church. After both have confirmed that neither are committing bigamy, they give the go-ahead.

Sometimes I think it helps to remember that we are really just in the record-keeping business.

-- 
Kenneth Downs
Secure Data Software, Inc.
(Ken)nneth_at_(Sec)ure(Dat)a(.com)