Exam 5: Advanced Data Modeling

The extended entity relationship model (EERM)is sometimes referred to as the ____.

The "____" characteristic of a primary key states that: The PK must uniquely identify each entity instance.A primary key must be able to guarantee unique values.It cannot contain nulls.

____________________ completeness means that not every supertype occurrence is a member of a subtype.

The default comparison condition for the subtype discriminator attribute is the ____ comparison.

In what two cases are composite primary keys particularly useful?

The most common design trap is known as a(n)____________________.

Overlapping subtypes are subtypes that contain a unique subset of the supertype entity set.

The ____________________ constraint specifies whether each entity supertype occurrence must also be a member of at least one subtype.

The primary key's main function is to uniquely identify a(n)____ within a table.

Within a specialization hierarchy,a supertype can exist only within the context of a subtype.

____ data refer to data whose values change over time and for which you must keep a history of the data changes.

At the implementation level,the supertype and its subtype(s)depicted in the specialization hierarchy maintain a 1:1 relationship.

Partial completeness is symbolized by ____.

A ____ occurs when you have one entity in two 1:M relationships to other entities,thus producing an association among the other entities that is not expressed in the model.

Implementing non-overlapping subtypes requires the use of one discriminator attribute for each subtype.

If you use a surrogate key,you must ensure that the candidate key of the entity in question performs properly through the use of "____________________" and "not null" constraints.

Subtypes that contain nonunique subsets of the supertype entity set are known as ____________________ .

Composite keys are useful as identifiers of weak entities,where the weak entity has a strong ____________________ relationship with the parent entity.

The "____" characteristic of a primary key states that: The PK should not have embedded semantic meaning.An attribute with embedded semantic meaning is probably better used as a descriptive characteristic of the entity rather than as an identifier.

Specialization is based on grouping ____________________ characteristics and relationships of the subtypes.