Re: Modelling Disjoint Subtypes
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sat, 24 Mar 2007 20:21:54 GMT
Message-ID: <CLfNh.14690$PV3.151739_at_ursa-nb00s0.nbnet.nb.ca>
>
> Ha ha, I forgot to mention the entire motivation for the above,
> which is that you can drop the t column from S1 completely.
Date: Sat, 24 Mar 2007 20:21:54 GMT
Message-ID: <CLfNh.14690$PV3.151739_at_ursa-nb00s0.nbnet.nb.ca>
Marshall wrote:
> On Mar 24, 11:13 am, "Marshall" <marshall.spi..._at_gmail.com> wrote:
>
>>We can combine c2 and c3 to rewrite the fk that enforces >>the subtype relationship. >> >> constraint c3': foreign key(id, subtype1) references P(id, t)
>
> Ha ha, I forgot to mention the entire motivation for the above,
> which is that you can drop the t column from S1 completely.
How then do you extend it to allow authors as well as sellers? etc. Received on Sat Mar 24 2007 - 21:21:54 CET