Saturday, September 17, 2022

NEW "DATA MODELS" PART 1 (t&n)

Note: "Then & Now" (T&N) is a new version of what used to be the "Oldies but Goodies" (OBG) series. To demonstrate the superiority of a sound theoretical foundation relative to the industry's fad-driven "cookbook" practices, as well as the evolution/progress of RDM, I am re-visiting my 2000-06 debunkings, bringing them up to my with my knowledge and understanding of today. This will enable you to judge how well my arguments have held up and appreciate the increasing gap between scientific progress and the industry’s stagnation, if not outright regress.

 

“Codd's aim was to free programmers from having to know the physical structure of data. Our aim is to free them in addition from having to know its logical structure.”

                                                          --Simon Williams, LazySoft

This series is a re-publication of several DBDebunk 2001 posts in response to Simon Wlliams' so-called "Associative Model of Data", academic claims of superiority over RDM ("The Associative Data Model Versus the Relational model") and predictions of the demise of the latter ("The decline and eventual demise of the Relational Model of Data").

Part 1 is the email exchange among myself (FP), Chris Date (CJD) and Lee Fesperman (LF) in reaction to Williams' claims that started the whole thing.

Monday, September 12, 2022

DATABASE DESIGN: THE STATE OF KNOWLEDGE IN THE INDUSTRY

Can you identify all the fallacies and misconceptions in the following online exchange? What is the elephant in the room?
Q: “I have done data normalization on dummy data and would like to know if I did it correctly. If it is done correctly, I would also like to ask two things below, because it is about 3NF.

1NF: This table should be 1NF. 

2NF: I selected composite key (userID and Doors) as they represent minimal candidate key and got three tables applying FD rule.

 

3NF: Applying the rule of transitive dependency on 1st table in 2NF, I got out 4 tables (showing only first two, because the last two remain unchanged).

Questions: Is this database normalisation correct? If not could you point me where I did mistake? If answer on first question is True: Should the last table in 3NF be transformed into two tables, given it is not in correct Third normal form. Two non-key atributes have FD keycode -> accessGroup.”
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