Re: Navigation vs Relational operators

Paul Vernon wrote:
>
> Personally, (I think) I much prefer tools that make logical navigation
> visible to the users, so that you don't get a discontinuity between 'simple'
> queries that can be done without logical navigation, and those that require
> it. In other words, I'm probably with Codd :- "the universal-relation model
> fails completely as an alternative to the relational model."

Well, Moshe Vardi never claimed it was. Could be that Jeff Ullman did, though. At a few occasions I've heard him make a remark about it that gave the impression to me that he was still a little bit sore over this.

I don't really have a strong opinion either way. I'm sure that in some limited cases the UR approach works splendidly (simple schema, simple SPJ questions) but in other cases it will make things actually more difficult than necessary.

Apologies for being so non-argumentative. :-)

• Jan Hidders