Module 4

Which of the following statements best defines a recursive entity? a. A recursive relationship is one in which a relationship can exist between occurrences of the same entity set. b. A recursive relationship is one in which a relationship can exist between occurrences of the same entity set or another entity. c. A recursive relationship is one in which one or more attributes can exist between occurrences of the same entity set. d. A recursive relationship is one in which one or more attributes can exist between occurrences of the same entity set or another entity.

a. A recursive relationship is one in which a relationship can exist between occurrences of the same entity set.

Which of the following is not a true statement about entities? a. An entity is an object of interest to the end designer. b. An entity refers to the entity set and not to a single entity occurrence. c. The ERM refers to a table row as an entity instance or entity occurrence. d. The entity name, a noun, is usually written in all capital letters.

a. An entity is an object of interest to the end designer.

A multivalued attribute is _____. a. an attribute that can have many values. b. an attribute represented by double values. c. an attribute that can have many entities. d. All of the above

a. an attribute that can have many values.

Which of the following statements best defines cardinality? a. Cardinality expresses the maximum number of entity occurrences associated with one occurrence of the related entity. b. Cardinality expresses the minimum number of entity occurrences associated with one occurrence of the related entity. c. Cardinality expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity. d. Cardinality expresses number of entity occurrences associated with one occurrence of the related entity.

c. Cardinality expresses the minimum and maximum number of entity occurrences associated with one occurrence of the related entity.

Building an ERD involves the following activities except a. Creating a detailed narrative of the organization's description of operations. b. Identifying the business rules based on the description of operations. c. Identifying all entities and relationships from the business rules. d. Identifying the attributes and primary keys that adequately describe the entities.

c. Identifying all entities and relationships from the business rules.

If an entity can exist apart from all of its related entities, then _____. a. it is existence-independent. b. it can be referred to as a strong entity. c. it can be referred to as a regular entity. d. All of the above

d. All of the above

A single-valued attribute _____. a. may be a composite attribute because it can be subdivided into several parts. b. is not necessarily a simple attribute. c. is an attribute that can have only a single value. d. All the above

d. All the above

Which of the following statements best defines optional attribute? a. An optional attribute is an attribute that requires a value and can be left empty. b. An optional attribute is an attribute that requires a value and can be an optional key. c. An optional attribute is an attribute that does not require a value and can be an optional key. d. An optional attribute is an attribute that does not require a value and can be left empty.

d. An optional attribute is an attribute that does not require a value and can be left empty.

Which of the following is a rare occurrence of a relationship degree? a. Unary relationship b. Binary relationship c. Ternary relationship d. Four-degree relationship

d. Four-degree relationship

A derived attribute is _____. a. an attribute whose value is part of another attribute. b. an attribute whose value is related to other attributes. c. an attribute whose value is composed of other attributes. d. an attribute whose value is calculated from other attributes.

d. an attribute whose value is calculated from other attributes.