Friday, February 12, 2021

TYFK: What Is a Relational Database and Why Is It Important?



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:
  • 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.”
--What is a relational database and why is it important, Quora.com

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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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