Note: Each "Test Your Foundation Knowledge" post presents one or more misconceptions about data fundamentals. To test your knowledge, first try to detect them, then proceed to read our debunking, which is based on the current understanding of the RDM, distinct from whatever has passed for it in the industry to date. If there isn't a match, you can acquire the knowledge by checking out our POSTS, BOOKS, PAPERS, LINKS (or, better, organize one of our on-site SEMINARS, which can be customized to specific needs).
“The most popular data model in DBMS is the Relational Model. It is more scientific a model than others. This model is based on first-order predicate logic and defines a table as an n-ary relation. The main highlights of this model are:--What is a relational database and why is it important, Quora.com
- Data is stored in tables called relations.
- Relations can be normalized.
- In normalized relations, values saved are atomic values.
- Each row in a relation contains a unique value.
- Each column in a relation contains values from a same [sic] domain.”
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LATEST UPDATES
-12/24/20: Added 2021 to the POSTS page
-12/26/20: Added “Mathematics, machine learning and Wittgenstein to LINKS page
LATEST PUBLICATIONS (order from PAPERS and BOOKS pages)
- 08/19 Logical Symmetric Access, Data Sub-language, Kinds of Relations,
Database Redundancy and Consistency, paper #2 in the new UNDERSTANDING THE
REAL RDM series.
- 02/18 The Key to Relational Keys: A New Understanding, a new edition
of paper #4 in the PRACTICAL DATABASE FOUNDATIONS series.
- 04/17 Interpretation and Representation of Database Relations, paper
#1 in the new UNDERSTANDING THE REAL RDM series.
- 10/16 THE DBDEBUNK GUIDE TO MISCONCEPTIONS ABOUT DATA FUNDAMENTALS, my
latest book (reviewed by Craig Mullins, Todd Everett, Toon Koppelaars, Davide
Mauri).
USING THIS SITE
- To work around Blogger limitations, the labels are mostly abbreviations or
acronyms of the terms listed on the FUNDAMENTALS
page. For detailed
instructions on how to understand and use the labels in conjunction with the
that page, see the ABOUT
page. The 2017 and 2016 posts,
including earlier posts rewritten in 2017 were relabeled accordingly. As other
older posts are rewritten, they will also be relabeled. For all other older
posts use Blogger search.
- The links to my columns there no longer work. I moved only the 2017 columns
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work or not.
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Misconceptions
- The RDM is not the most popular data model.
- There are no "others" -- no other data models that comply with the definition by Codd, who invented the concept.
- By definition a data model cannot be "less scientific".
- The RDM is not based on just FOPL, which does not define "a table as an n-ary relation", and relations don't have rows and columns.
- Data is stored neither in tables, nor in relations;
- Relations do not require normalization (if they do, they are not relations).
- Value atomicity is misunderstood.
Note: I will not publish or respond to anonymous comments. If you have something to say, stand behind it. Otherwise don't bother, it'll be ignored.
References
Data Sublanguage vs. SQL
"Multi-model DBMSs" is an Empty Set
Theory: As Far From Religion As One Can Get
What Is a Data Model and What It Is Not
Understanding Relations: Tables, So What?
What Relations Really Are and Why They Are Important
Data and Meaning: The RDM Is Applied Theory
Physical Independence series
Normalization and Further Normalization series
First Normal Form in Theory and Practice series
Simple Domains and Value Atomicity
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