Re: On view updating

On Tue, 21 Sep 2004 13:05:03 -0700, Costin Cozianu <c_cozianu_at_hotmail.com> wrote:

>There's no such thing as "virtual variables" in PL theory.

In that case views are variables. Views and base relvars are interchangeable and indistinguishable. An user can't know if he is working with a table or a view.

BTW PL theory is not closed and we can introduce "virtual variables" and even weirder things.

>- views do not denote a "store".

Why not?

>as opposed to views, tables, which also have a name:
>
>- denote a "store". A place in the global state holding a value that can
>be changed.

If you consider closed views as views they also denote a "store" in the external level.

Do you consider closed views as tables?

>Therefore, here you have your trivial distinction in all imperative
>languages between a "store" (variable, possibly aliased or non-aliased)
>which is your lvalue, and an expression.

An aliased table is something very similar to a view. If we don't have table aliases we can do the same with views. I don't see a clear logical difference between a table alias and a view like: create view xxx as select * from myTable

If something looks like a variable, smells like a variable and behaves like a variable then it is a variable :)

Regards Received on Tue Sep 21 2004 - 18:49:18 CDT