Primary Key

A Primary Key is a Key that uniquely identifies an occurrence of an Entity. Every database entity requires a primary key, which is used to ensure that occurrences are unique in a database table and to define relationships between modeled entities.

Characteristics

Characteristics

  

Icon:

Primary key

Object type code:

key

Main Development Object?

No

Part of:

Modeled Entity

Contains:

Property

Generalization:

Key

Specializations:

—

Compilation Output:

—

Specialization

Primary Key specializes Key in the following ways:

  • It has the Type property set to Primary.

The first key defined for an entity must be the primary key.