Re: Stupid Database Tricks

From: Jan Hidders <hidders_at_gmail.com>
Date: Wed, 13 Jun 2007 05:53:41 -0700
Message-ID: <1181739221.341018.321220_at_j4g2000prf.googlegroups.com>


On 13 jun, 10:41, vldm10 <vld..._at_yahoo.com> wrote:
> [...] Although, regarding that you are
> knowledgeable person I would like to know what is in your opinion
> reinvented (or looks like it) in my "model". You can roughly present
> it or one by one.

The ideas of :
1. Adding a special key to relations that identifies the entities or relationships represented by the tuples in the relation. 2. Using the presence of this key to split everything as much as possible into binary relations.

These are old ideas, and have already been rejected before. I have not seen any argumentation by you that explains why this would now have become a good idea.

Btw. did you realize that for a relation R(K, A_1, ..., A_n) where {K} is a superkey, it always holds that the relation equals the joins of R(K, A_1), ..., R(K, A_n)? Any assumptions about mutual independence are not necessary. Also note that such a relation is not necessarily in 5NF if {A_1, ..., A_n} are mutually independent, or even in 4NF, for that matter.

  • Jan Hidders
Received on Wed Jun 13 2007 - 14:53:41 CEST

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