Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Modelling Disjoint Subtypes

Re: Modelling Disjoint Subtypes

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Sun, 25 Mar 2007 12:07:42 GMT
Message-ID: <iCtNh.14894$PV3.154385@ursa-nb00s0.nbnet.nb.ca>


Mike wrote:

>>Could anyone please provide a meaningful relational design example where
>>disjoint entity subtype/supertype  hierarchy would truly be beneficial ?  I
>>am aware of Pascal's example but do not find it convincing.

>
> The fundamental insight is that the two (or more) entities in question
> are not
> identical, but they're not utterly unlike each other. I'm pretty sure
> Pascal
> makes that point.

I think the more enlightening observation is to note the end result is merely two relations. Whether one wants to consider them as a sub-anything or super-anything is more psychological than anything else. Received on Sun Mar 25 2007 - 07:07:42 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US