Definicja hierarchical relationship type

Co znaczy HIERARCHICAL RELATIONSHIP TYPE:

A defined connection between two entity types.

A hierarchical relationship type exists when:

The existence of the target entity type depends on the source entity type, that is, the lifespan of an instance of the target entity type is less than or equal to the lifespan of the instance of the source entity type. The target entity type is created by the source entity type, that is, the source entity type has direct influence on the attributes. The target entity type is a semantic refinement of the source entity, that is, the target entity type is a classification of the source entity type, which describes it more restrictively.