Re: teaching relational basics to people, questions
From: Bob Badour <bbadour_at_pei.sympatico.ca>
Date: Tue, 22 Dec 2009 00:01:24 -0400
Message-ID: <4b304499$0$5332$9a566e8b_at_news.aliant.net>
>>Jan Hidders wrote:
>>
>>>On 16 nov, 20:42, Sampo Syreeni <de..._at_iki.fi> wrote:
>>
>>>>So now I bump into my first real surprise, and the chills immediately
>>>>go down my spine. That's Date et al.'s answer regarding the
>>>>implications between 6NF and DK/NF,
>>>
>>>athttp://www.dbdebunk.com/page/page/621935.htm
>>>
>>>>. In there they flat out state that DK/NF doesn't imply 6NF.
>>
>>>>So, my first question is, can this really be true? I mean, this seems
>>>>highly suspect to me: since 6NF is a normal form like any other
>>
>>I don't think so. It's hard fo me to tell, because I just did the
>>required math and it turns out don't have $60 to spend on the book
>>which contains the definition of 6NF required for this discussion,
>>but if I can get by the Google Books preview, it appears to involve some
>>degree of interpretation of domain values (as being totally ordered).
>>Normal normal forms don't do this.
Date: Tue, 22 Dec 2009 00:01:24 -0400
Message-ID: <4b304499$0$5332$9a566e8b_at_news.aliant.net>
Jan Hidders wrote:
> On 21 dec, 23:07, r..._at_raampje.lan (Reinier Post) wrote: >
>>Jan Hidders wrote:
>>
>>>On 16 nov, 20:42, Sampo Syreeni <de..._at_iki.fi> wrote:
>>
>>>>So now I bump into my first real surprise, and the chills immediately
>>>>go down my spine. That's Date et al.'s answer regarding the
>>>>implications between 6NF and DK/NF,
>>>
>>>athttp://www.dbdebunk.com/page/page/621935.htm
>>>
>>>>. In there they flat out state that DK/NF doesn't imply 6NF.
>>
>>>>So, my first question is, can this really be true? I mean, this seems
>>>>highly suspect to me: since 6NF is a normal form like any other
>>
>>I don't think so. It's hard fo me to tell, because I just did the
>>required math and it turns out don't have $60 to spend on the book
>>which contains the definition of 6NF required for this discussion,
>>but if I can get by the Google Books preview, it appears to involve some
>>degree of interpretation of domain values (as being totally ordered).
>>Normal normal forms don't do this.
> > Wikipedia is your friend: > > <http://en.wikipedia.org/wiki/Sixth_normal_form> > > Whether you can call it a normal form or not is of course largely a > matter of definition, but it clearly is different from the other ones. > It does for example not remove redundancy or update anomalies, which > was pretty much the whole point of the other normal forms.
-- is there something in it for them, like maybe bailouts, if they can panic us into doing something politically to cover them? November 19, 2007 - John S Bolton http://tinyurl.com/y9e4vxhReceived on Tue Dec 22 2009 - 05:01:24 CET