Logical Data Modeling - Primary Key (Id, Name)

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.

Data Type

Numeric

A numeric primary key is called an id

Textual

A textual primary key is called a name

Type

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.

Relationship

Value

Synthetic / Surrogate key

Natural

Implementation


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