Sunday, January 30, 2022


 “A data model is a collection of concepts ... used to describe the structure of a types, relationships and basically a conceptualization between attributes and entities ...
The building blocks in the data model are as follows:
  • Entity − An entity represents a particular type of object in the real world.
  • Entity set − Sets of entities of the same type which share the same properties are called entity Sets.
  • Attribute − An attribute is a characteristic of an entity.
  • Constraints − A constraint is a restriction placed on the data. It is helpful to ensure data integrity.
  • Relationship − A relationship describes an association among entities.

Fallacies, Misconceptions and Confusion

  • A data model:

- does not describe (just) the structure of a database.
- is not "a conceptualization between attributes and entities" (whatever that means).

  • Entities, entity sets and relationships are not building blocks of a data model.


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01/21 Read My Lips: If There's NULLs, It's Not Relational

01/16 OBG: No Understanding without Foundation Knowledge Part 3 -- Debunking an Online Exchange 3

01/08 OBG: No Understanding without Foundation Knowledge Part 3 -- Debunking an Online Exchange 2

01/01 Schema and Performance: Never the Twain Shall Meet

02/08 Aded 2021 posts to POSTS page.

- 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).

- 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 to dbdebunk, within which only links to sources external to AllAnalytics may work or not.

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Fundamentals and Debunking -- References

A data model is a theory of data used to formalize conceptual models of reality as logical models for database representation. It defines not just the database structure, but also its manipulation for inferential purposes and integrity for consistency with conceptual models and correctness of inferences.

Levels of representation

Conceptual: entity,  entity group,  property,  property in context,  relationship
Logical (RDM): tuple,  relation, domain,  attribute,  constraint

Note: Entity is a primitive atomic object, entity group is a derived compound object at the conceptual level. RDM domains are distinct from programming data types.

Components of a data model:

Structure (RDM: relation -- domains, attributes, tuples).
Integrity (RDM: constraints -- domain, attribute, tuple, multi-tuple, multi-relation).
Manipulation (RDM: relational algebra -- restrict, project, join, ...)

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