Exam 5: Advanced Data Modeling

Usually,a data modeler uses a natural identifier as the ____________________ of the entity being modeled,assuming that the entity has a natural identifier.

The relationships depicted within the ____ are sometimes described in terms of "is-a" relationships.

A specialization hierarchy can have ____ level(s)of supertype/subtype relationships.

The _____________________________________________ is the result of adding more semantic constructs to the original entity relationship (ER)model.

Entity subtypes do not inherit the relationships in which the supertype entity participates.

Composite primary keys are particularly useful as identifiers of composite entities,where each primary key combination is allowed ____________________ in the M:N relationship.

The relationships depicted within the specialization hierarchy are sometimes described in terms of "is-a" relationships.

An entity cluster is considered "virtual" or "____________________" in the sense that it is not actually an entity in the final ERD.

A ____ key is a real-world,generally accepted identifier used to uniquely identify real-world objects.

Explain the "no change over time" characteristic of a good primary key.