1. (Mt) – Please answer the questions
Unformatted Preview 99 Chapter Review Key Terms Associative entity 76 Attribute 69
Binary relationship 80 Business rule 60 Cardinality constraint 84 Composite attribute 70
Composite identifier 71 Degree 78 Derived attribute 71 Entity 65 Entity instance 65 Entity-
relationship diagram (E-R diagram) 56 Entity-relationship model (E-R model) 56 Entity
type 65 Fact 63 Identifier 71 Identifying owner 67 Identifying relationship 67 Maximum
cardinality 84 Minimum cardinality 84 Multivalued attribute 70 Optional attribute 69
Relationship instance 75 Relationship type 75 Required attribute 69 Simple (or atomic)
attribute 70 Strong entity type 66 Term 63 Ternary relationship 81 Time stamp 87 Unary
relationship 78 Weak entity type 66 Review Questions 2-1. Define each of the following
terms: a. entity type b. entity-relationship model c. entity instance d. attribute e.
relationship type f. strong entity type g. multivalued attribute h. associative entity i.
cardinality constraint j. weak entity k. identifying relationship l. derived attribute m.
business rule 2-2. Match the following terms and definitions. composite attribute a.
uniquely identifies entity instances associative entity b. relates instances of a single unary
relationship entity type weak entity c. specifies maximum and minimum attribute number
of instances entity d. relationship modeled as an entity type relationship type e. association
between entity types cardinality f. collection of similar entities constraint g. number of
participating entity types degree in relationship identifier h. property of an entity entity
type i. can be broken into component parts ternary j. depends on the existence of another
bill-of-materials entity type k. relationship of degree 3 l. many-to-many unary relationship
m. person, place, object, concept, event 2-3. Contrast the following terms: a. stored attribute;
derived attribute b. simple attribute; composite attribute c. entity type; relationship type d.
strong entity type; weak entity type e. degree; cardinality f. required attribute; optional
attribute g. composite attribute; multivalued attribute h. ternary relationship; three binary
relationships 2-4. Give four reasons why many system designers believe that data modeling
is important and arguably the most important part of the systems development process. 2-
5. Give four reasons why a business rules approach is advocated as a new paradigm for
specifying information systems requirements. 2-6. Explain where you can find business
rules in an organization. 2-7. State six general guidelines for naming data objects in a data
model. 2-8. State four criteria for selecting identifiers for entities. 2-9. Why must some
identifiers be composite rather than simple? 2-10. State three conditions that suggest the
designer should model a relationship as an associative entity type. 2-11. List the four types
of cardinality constraints, and draw an example of each. 2-12. Give an example, other than

2. those described in this chapter, of a weak entity type. Why is it necessary to indicate an
identifying relationship? 2-13. What is the degree of a relationship? List the three types of
relationship degrees described in the chapter and give an example of each. 2-14. Give an
example (other than those described in this chapter) for each of the following, and justify
your answer: a. derived attribute b. multivalued attribute c. atomic attribute d. composite
attribute e. composite identifier attribute f. optional attribute 2-15. Give an example of each
of the following, other than those described in this chapter, and clearly explain why your
example is this type of relationship and not of some other degree. a. ternary relationship b.
unary relationship 2-16. Give an example of the use of effective (or effectivity) dates as
attributes of an entity. 2-17. State a rule that says when to extract an attribute from one
entity type and place it in a linked entity type. 100 2-18. What are the special guidelines for
naming relationships? 2-19. In addition to explaining what action is being taken, what else
should a relationship definition explain? 2-20. For the Manages relationship in Figure 2-12a,
describe one or more situations that would result in different cardinalities on the two ends
of this unary relationship. Based on your description for this example, do you think it is
always clear simply from an E-R diagram what the business rule is that results in certain
cardinalities? Justify your answer. 2-21. Explain the distinction between entity type and
entity instance. 2-22. Why is it recommended that every ternary relationship be converted
into an associative entity? Problems and Exercises Includes Belongs Is responsible for 2-23.
A cellular operator needs a database to keep track Family member of its customers, their
subscription plans, and the handsets (mobile phones) that they are using. The E-R diagram
in Figure 2-24 illustrates the key Manufacturer Customer Handset Type entities of interest
to the operator and the relationships between them. Based on the figure, answer the
following questions and explain the rationale for your response. For each question, identify
the element(s) in the E-R diagram that you used to Handset determine your answer. a. Can a
customer have an unlimited number of plans? b. Can a customer exist without a plan? c. Is it
possible to create a plan without knowing Operating System who the customer is? d. Does
the operator want to limit the types of handPlan sets that can be linked to a specific plan
type? e. Is it possible to maintain data regarding a handset without connecting it to a plan? f.
Can a handset be associated with multiple plans? Plan Type g. Assume a handset type exists
that can utilize multiple operating systems. Could this situation be accommodated within
the model included in FIGURE 2-24 Diagram for Problem and Exercise 2-23 Figure 2-24? c.
In the context specified in 2a and 2b, better information h. Is the company able to track a
manufacturer is needed regarding the relationship between a book without maintaining
information about its handsets? and its authors. Specifically, it is important to record i. Can
the same operating system be used on multiple the percentage of the royalties that belongs
to a specific handset types? author, whether or not a specific author is a lead author j. There
are two relationships between Customer and of the book, and each author’s position in the
sequence Plan. Explain how they differ. of the book’s authors. k. Characterize the degree and
the cardinalities of the d. A book (see 2a) can be part of a series, which is also relationship
that connects Customer to itself. Explain identified as a book and has its own ISBN number.
One its meaning. book can belong to several sets, and a set consists of at l. Is it possible to
link a handset to a specific customer in least one but potentially many books. a plan with

3. multiple customers? e. A piano manufacturer wants to keep track of all m. Can the company
track a handset without identifying the pianos it makes individually. Each piano has its
operating system? an identifying serial number and a manufacturing 2-24. For each of the
descriptions below, perform the followcompletion date. Each instrument represents exactly
ing tasks: one piano model, all of which have an identificai. Identify the degree and
cardinalities of the relationship. tion number and a name. In addition, the company ii.
Express the relationships in each description graphically wants to maintain information
about the designer with an E-R diagram. of the model. Over time, the company often manua.
A book is identified by its ISBN number, and it has a factures thousands of pianos of a
certain model, and title, a price, and a date of publication. It is published by the model
design is specified before any single piano a publisher, which has its own ID number and a
name. exists. Each book has exactly one publisher, but one publisher f. A piano
manufacturer (see 2e) employs piano techtypically publishes multiple books over time.
nicians who are responsible for inspecting the b. A book (see 2a) is written by one or
multiple authors. instruments before they are shipped to the customEach author is
identified by an author number and has ers. Each piano is inspected by at least two
technicians a name and date of birth. Each author has either one (identified by their
employee number). For each sepaor multiple books; in addition, occasionally data are rate
inspection, the company needs to record its date needed regarding prospective authors who
have not and a quality evaluation grade. yet published any books. HW #02 Assignment Due
September 16 at 11:55 PM Answer question 2-2, 2-6, 2-7, 2-10, 2-18, 2-21, 2-22, 2-23