Re: Transforming 1-1-M Ternary Relationships into Logical

if you scroll down to page 5 you'll see what I am refering too..

miklesw_at_gmail.com wrote:
> 1-1-M = Ternary Relationship (A,B,C)
>
> A can have 1 B and 1 C
> B can have Many As and Cs
> C can have Many As and Bs
>
> http://groups.google.com.mt/group/comp.databases.theory/tree/browse_frm/thread/33c2956edca34a75/0e88b26bd53dcb2c?rnum=1&hl=en&_done=%2Fgroup%2Fcomp.databases.theory%2Fbrowse_frm%2Fthread%2F33c2956edca34a75%2F0e88b26bd53dcb2c%3Fhl%3Den%26#doc_b95911d131acf57a
>
>
>
> Bob Badour wrote:
> > miklesw_at_gmail.com wrote:
> > > What do you mean by "A pointer that allows to design cardinalities"?
> > > I'm not following..
> > >
> > > Cimode wrote:
> > >
> > >>You are using an incorrect terminology. You believe a relationship is
> > >>a pointer that allows to design cardinalities (it is not). The proper
> > >>way for you to deal with the problem you are describing is to do some
> > >>serious reading about relational model...Here is the reference...Hope
> > >>this helps...
> > >>
> > >>Introduction to Database Theory by CJ DATE
> > >>
> > >>
> > >>miklesw_at_gmail.com wrote:
> > >>
> > >>>Most text books state that Ternary relationships are implemented as a
> > >>>table with FKs for all the relations.. i was wondering how are 1-1-M
> > >>>relationships implemented..
> > >>>
> > >>>It seems pointless to me... In 1-M binary relationships.. the FK is
> > >>>placed on the M end...
> > >>>In this case it would make sense to put 2 FKs in the Many end..
> > >>>
> > >>>What is the proper way of implementing this?
> > >>>
> > >>>Tnx,
> > >>>
> > >>>Mike
> >
> > Hi Mike,
> >
> > Cimode is a crank. In general, you can safely ignore him; however, his
> > pointer to Chris Date is sound.
> >
> > I suspect the reason you have not received any better responses is
> > nobody really has any idea what you are talking about.
> >
> > If you have any 1-1 relative cardinality between two relations, you can
> > reduce that into a single relation, which would seem to leave you with a
> > simple 1-M foreign key reference. However, I am not confident that I
> > even know what you mean by 1-1-M.
Received on Wed Oct 04 2006 - 18:58:36 CEST