Sunday, June 18, 2017

This Week

1. Database Truth of the Week

"The RDM is a formal system. It has two parts.
  • The Deductive Subsystem: the formal language
  • The Interpretation Subsystem i.e., the application--of that language
Without an interpretation subsystem there is no possibility of applying the formal system and it remains an abstract game of symbols.
Semantics is about applying the RDM to some subject. In effect, what you do is restrict the power of the abstract formalism so that it is more closely aligned with your intended use. That means you are using constraints to limit the vocabulary to the subject matter (and making it finite and usually fairly small) and restricting the possible interpretations that can be used consistently with the resulting subset of the formalism." --David McGoveran


2. What's Wrong With This Database Picture?

"This confusion of entities vs. attributes has been with us a long time ... a paper discussed this dilemma in 1939 [and] proposed calling the thing, which we could not determine whether it was an entity or an attribute, an "entribute.
...
William Kent's DATA AND REALITY (1978) is devoted to "attributes" and (in my words)  he confesses that he can not distinguish between "relationships" and "attributes". Thus, the later might be completely redundant.
...
I have since come to realize that you must have the relationship first--the notion of an attribute presumes a relationship, so we must define that first. In fact we must also define the exclusivity/multiplicity of that relationship (in both directions for a binary relationship) before we can determine how to put the information into tables. In reality, we are not modeling objects/entities/attributes, [ X ], [ A ], etc. at all in the relational model, we are modeling a bunch of relationships, say [ X | A ], [ X | B ], etc. mashed together into a table [ X | A | B | ...], hence perhaps Codd was correct in calling it a "relation", a bunch of relationships.
...
Furthermore, the relational model has no relationships since Codd decreed that all relationships must be represented by foreign keys, which are exactly the same as "attributes." Interesting that most people think of relationships as being the distinguishing characteristic of a relational model and it is not All of this is handled explicitly and correctly in ORM--we model objects (each one appears only once in a data model diagram) and relationships. There are no attributes. As I said before, an attribute is an object playing a role in a relationship with another object.
...
Looking back into original relational model (by Codd, Date, etc.) is not it funny, that the term relation is implicitly mapped (in our minds) to a table of a database? If (loosely speaking) a relationship in our conventional data modeling is represented by a foreign key in a table (and combining both points together) --should a table (relation) consists only of foreign keys?" --LinkedIn.com


3. To Laugh or Cry?

"I am pretty new in database administration and i am currently working on a project for creating an automating managing system for a school. So I am working in database design. Can someone please tell me how many table i need and if possible the name of all these tables?" --What is the number and the name of all tables to use for a school managing system? --StackExchange.com
   

4. Publications


The first paper in the new UNDERSTANDING OF THE REAL RDM series, Interpretation and Representation of Database Relations is available for ordering here.

My book, THE DBDEBUNK GUIDE TO MISCONCEPTIONS ABOUT DATA FUNDAMENTALS is available to order here.

Reviews

Craig Mullins
Todd Everett
Toon Koppelaars
Davide Mauri

5. Oldies but Goodies

The XML Bug

6. Of Interest


And Now for Something Completely Different


This week @The PostWest: Evidence for the demise of America and Western civilization.

Pinch Me of the Week: Accused of Underpaying Women, the Big Data Company of Record Says "It's Too Expensive To Get Wage Data"

The Corporate Technology Dystopia



Book of the Week:  Seth Stephens-Davidowitz, EVERYBODY LIES: BIG DATA, NEW DATA AND WHAT THE INTERNET CAN TELL US ABOUT WHO WE REALLY ARE
Review: Persuasive proof that America is full of racist and selfish people


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