Logical Data Modeling - Primary Key (Id, Name)

1 - About

A Primary Key is a key that identify indefinitely uniquely an element (entity or a relationship) in their local scope.

It's a part of the fully qualified identifier.

3 - Data Type

3.1 - Numeric

A numeric primary key is called an id

3.2 - Textual

A textual primary key is called a name

4 - Type

4.1 - Entity

A entity key is a key that:

  • identify uniquely a single entity
  • doesn't change over time. If the primary key has a chance – however remote – of changing, well, then it is NOT the primary key. This would be like you changing your DNA halfway through your life.
  • define, in dimensional modeling, the lowest level of an entity

This is one or a group of attributes such that the relationship between the entity set and the attribute value sets has a one-to-one cardinality.

4.2 - Relationship

5 - Value

5.1 - Synthetic / Surrogate key

5.2 - Natural

Logical Data Modeling - Natural Key

6 - Implementation


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