Sunday, January 30, 2022

TYFK: Nobody Understands What a Data Model Is



 “A data model is a collection of concepts ... used to describe the structure of a database...data types, relationships and constraints...is 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.
--TutorialsPoint.com

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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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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