Database Processing, 15e (Kroenke)
Chapter 5: Data Modeling with the Entity-Relationship Model
1) A data model is a plan for a database design.
2) The method of constructing data models used in the text is the extended entity-relationship (E-
R) model.
3) An entity is something that users want to track.
4) Entities of a given type are grouped into entity classes.
5) An entity class is described by the structure of the entities in that class.
6) An entity instance is an occurrence of a particular entity.
7) An entity instance of an entity class is the representation of a particular entity, and is described
by the values of the attributes of the entity.
8) An identifier of an entity instance is one or more attributes that name or identify entity
instances.
9) A compound identifier is an identifier consisting of two or more attributes.
10) In E-R modeling, an attribute describes the characteristics of an entity.
11) In E-R modeling, entities within an entity class may have different attributes.
12) An identifier of an entity instance must consist of one and only one attribute.
13) A composite identifier is defined as a composite attribute that is an identifier.
14) An identifier serves the same role for a table that a key does for an entity.
15) Entities can be associated with one another in relationships.
16) The degree of a relationship is the number of entity classes in the relationship.
17) A binary relationship is a relationship between two or more entities.
18) Relationships of degree two are referred to as binary relationships.
19) The Information Engineering (IE) model created by James Martin is often referred to as the
IE Crowe’s Foot model.
20) In today’s E-R models, attributes of relationships are still used.
21) A single relationship class involves only one entity class.
22) A binary relationship is a relationship based on numerical entity instance identifiers.
23) The degree of a relationship is expressed as the relationship’s maximum cardinality.
24) When transforming a data model into a relational design, relationships of all degrees are
treated as combinations of binary relationships.
25) A principal difference between an entity and a table is that you can express a relationship
between entities without using foreign keys.
26) When designing a database, first identify the entities, then determine the attributes, and
finally create the relationships.
27) The notation 1:N shows a relationship’s maximum cardinalities.
28) Relationships are classified by their cardinality.
29) A relationship’s maximum cardinality indicates the maximum number of entities that can
participate in the relationship.
30) In an E-R model, the three types of maximum cardinality are 1:1, 1:N, and N:M.
31) In a 1:N relationship, the term parent refers to the N side of the relationship.
32) In a 1:N relationship, the parent entity is on the one side of the relationship, and the child
entity is on the many side of the relationship.
33) An entity’s minimum cardinality in a relationship indicates the number of entity instances
that must participate in the relationship.
34) An entity’s minimum cardinality in a relationship indicates whether or not an entity must
participate in the relationship.
35) In an E-R model, the three types of minimum cardinality are mandatory, optional, and
indeterminate.
36) An entity that represents something that can exist on its own is called a strong entity.
37) The E-R model includes a special type of strong entity called an ID-dependent entity.
38) An ID-dependent entity is an entity whose identifier includes the identifier of another entity.
39) ID-dependent entities are associated by a nonidentifying relationship.
40) A weak entity is an entity that cannot exist in the database without, and is logically
dependent upon, another type of entity also existing in the database.
41) ID-dependent entities are a common type of weak entity.
42) All weak entities must have a minimum cardinality of 1 on the entity on which it depends.
43) Subtypes and supertypes contain the same identifier and some other attributes.
44) An attribute that determines which subtype is appropriate is called a discriminator.
45) An exclusive subtype pattern has one supertype entity that relates to one or more subtype
entities.
46) Entities with an IS-A relationship should have the same identifier.
47) One example of a database design using an ID-dependent relationship is the association
pattern where a third entity may be added.
48) In a multivalued attribute pattern many different multivalued attributes can be created.
49) One example of a database design using an ID-dependent relationship is the
archetype/instance pattern.
50) Data modelers agree that weak, non-ID-dependent entities exist and are important.
51) Entities containing multivalued attributes are often represented using subtypes.
52) The supremetype entity contains the attributes that are common to all subtypes.
53) An attribute that determines which subtype is appropriate is called a discriminator.
54) Subtypes can be exclusive or inclusive.
55) Relationships between supertypes and subtypes are called IS-A relationships.
56) A recursive relationship occurs when an entity type has many relationships with other
recursive entities.
57) There are three types of recursive relationships: 1:1, 1:N, and N:M.
58) Recursive relationships only exist for one-to-one relationships.
59) Which of the following is not a good reason for designing a data model?
A) It’s easier to change things in the data model than it is in the actual DBMS.
B) The data model provides a simplified view of the database that can be shown to people who
don’t need to see all the details.
C) Creating a data model will help you understand the application area better.
D) The data model can be discarded after the database is operational.
60) Which of the following is not a key element of an E-R model?
A) Relationships
B) Entities
C) Objects
D) Attributes
61) Entities of a given type are grouped into an ________.
A) entity class
B) entity relationship
C) entity instance
D) entity attribute
62) An occurrence of a particular entity is called an ________.
A) entity class
B) entity relationship
C) entity instance
D) entity attribute
63) The characteristics of a thing are described by its ________.
A) identifiers
B) entities
C) objects
D) attributes