Re: NULLs: theoretical problems?

From: David Portas <>
Date: Fri, 17 Aug 2007 17:55:41 +0100
Message-ID: <>

"Brian Selzer" <> wrote in message news:llgxi.46607$
> "Jan Hidders" <> wrote in message
>> 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
Received on Fri Aug 17 2007 - 18:55:41 CEST

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