Re: NULLs: theoretical problems?

"Brian Selzer" <brian_at_selzer-software.com> wrote in message news:llgxi.46607$Um6.26793_at_newssvr12.news.prodigy.net...
>
> "Jan Hidders" <hidders_at_gmail.com> wrote in message
> news:1187305514.703264.214690_at_d55g2000hsg.googlegroups.com...
>>
>> Just a minor technicality. As far as I understand it an equality
>> constraint can be represented by two inclusion dependencies in both
>> directions, so I would say that it *is* supported by SQL. Anything I'm
>> missing?
>>
>
> Yes. SQL doesn't support multiple assignment. In order to get rows with
> new key values inserted, at least one of the constraints needs to be
> disabled.
>

SQL doesn't properly support relational assignment of either the single or multiple kind. As far as I'm aware however, multiple assignment of a sort could be possible via an updateable view. ie.:

INSERT INTO v (a,b) VALUES (1,1);

is potentially valid even if a and b belong to separate base tables. Or is there some absurd restriction that disallows this?

-- 
David Portas