Re: On view updating

From: Costin Cozianu <c_cozianu_at_hotmail.com>
Date: Tue, 21 Sep 2004 13:05:03 -0700
Message-ID: <2rbfroF18gl6lU1@uni-berlin.de>

>>Since 
>>relvars are "variables" and the rest are computed values,

>
>
> Views are variables too. Virtual variables but variables. Although a
> "closed view" has nothing of virtual to the user.
>
>

There's no such thing as "virtual variables" in PL theory.So to avoid confusion by "my imaginary model" vs. "your imaginary model" kind of debate let's enumerate some invariants across all reasonable models

• Views have a name
• A view denotes an expression that can be evaluated or composed with other expressions.
• views do not denote a "store".

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.

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. Received on Tue Sep 21 2004 - 15:05:03 CDT