Weak Entity Types

Posted by AJ × 03:43

An entity that does not have a key attribute. A weak entity must participate in an

identifying relationship type with an owner or identifying entity type.

Entities are identified by the combination of:

A partial key of the weak entity type

The particular entity they are related to in the identifying entity type.

Example:

A DEPENDENT entity is identified by the dependent’s first name, and the specific

EMPLOYEE with whom the dependent is related.

Name of DEPENDENT is the partial key.

DEPENDENT is a weak entity type.

EMPLOYEE is its identifying entity type via the identifying relationship type

DEPENDENT_OF

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