Exam 4: Entity Relationship Er Modeling

not only helps database designers to stay on track during the design process, it also enables them to pick up the design thread when the time comes to modify the design.

An entity is said to be -dependent if it can exist in the database only when it is associated with another related entity occurrence.

A relationship indicates the number of entities or participants associated with a relationship.

A(n) is the set of possible values for a given attribute.

The Crow's Foot notation is less implementation-oriented than the Chen notation.

The conceptual model can handle relationships and multivalued attributes.

In Chen notation, there is no way to represent cardinality.

The Chen notation identifies a weak entity by using a double-walled entity .

A weak relationship exists if the primary key of the related entity contains at least one primary key component of the parent entity.

The existence of a mandatory relationship indicates that the minimum cardinality is 0 or 1 for the mandatory entity.

Referential integrity and participation are both bidirectional, meaning that they must be addressed in both directions along a relationship.

The entity relationship diagram (ERD) represents the database as viewed by the end user.

Knowing the minimum and maximum number of occurrences is very helpful at the application software level.

In the original Chen notation, each attribute is represented by an oval with the attribute name connected to an entity rectangle with a line.

To simplify the conceptual design, most higher-order relationships are decomposed into appropriate equivalent? relationships whenever possible.