Re: Another view on analysis and ER
Date: Sat, 08 Dec 2007 21:00:25 GMT
Message-ID: <JBD6j.5404$jq2.1804_at_pd7urf1no>
JOG wrote:
...
> 1) Married(Husband:John, Wife:Jane, Instituion:Church)
> 2) EXISTS! x E marriages [ Husband(x, John) ^ Wife(x, Jane) ^
> Institution(x, Church) ]
>
> First one is marriage as a predicate, the second one the marriage as a
> thing, x. Which to choose, and when. And if it depends ona certain
> application, does picking one not bind us into that single conceptual
> model?
> ...
PMFJI, just like to point out that when either hits the machine, the variables husband, wife, institution are the same, one of Codd's central points I think.
Giving the relation a name is just a convenience and possibly an ill-considered choice to expand the name space of the possible types of relations in the db, eg., allow two relations with the same variables/attributes. Received on Sat Dec 08 2007 - 22:00:25 CET