Re: Transforming 1-1-M Ternary Relationships into Logical
Date: Wed, 04 Oct 2006 12:11:33 GMT
Message-ID: <VxNUg.46$cz.1450_at_ursa-nb00s0.nbnet.nb.ca>
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 - 14:11:33 CEST