Re: insert to projection
Date: Sun, 06 Sep 2009 18:40:18 GMT
Vadim Tropashko wrote:
> On Sep 4, 9:58 am, paul c <toledobythe..._at_oohay.ac> wrote:
>> ... We can delete from projection ...
> Are you suggesting projection being updatable in respect to deletion?
Not as things stand, at least not always, meaning not always with the conventional tables and relvars that have one predicate.
If I read that worksheet right, it means we can't delete <p 1, q 'a'> from a conventional table or relvar and expect <p 1> to be negated, which I don't argue with. (whereas I don't think anybody disagrees that we already can delete <p 1> and expect <p 1, q 'a'> to be negated.) Received on Sun Sep 06 2009 - 20:40:18 CEST