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

From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Wed, 04 Oct 2006 12:11:33 GMT
Message-ID: <VxNUg.46$cz.1450@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 - 07:11:33 CDT