Chapter 3

Question 1

Transaction Processing Systems (TPS)

Answer 1

Designed to support the processing of everyday operational business transactions (i.e., retrieving, adding, modifying, and deleting data)

Question 2

Decision Support Systems (DSS)

Answer 2

Specifically designed to aid managers in decision-making tasks

• -Contain data that has been accumulated over time to aid in trend analysis and forecasting
• -Data about subjects must be organized in such a way that it provides a unified, overall picture of all the important details about the subjects over time
• -Data warehouses are the most common example
• -Data marts are subsets of data warehouses designed to support a part of an organization

Question 3

Business rules

Answer 3

Can be used to define or constrain some aspect of a business’s structure or processes

Question 4

Data Modeling

Answer 4

is a design technique for capturing reality

Question 5

Conceptual Data Modeling

Answer 5

goal is to arrive at an understanding of the principal data sources and data elements of interest to the business or organization, and the relationships between the data sources, in order to satisfy requirements for information
tool is the Entity-Relationship Diagram (ERD)

Question 6

Logical Data Modeling

Answer 6

goal is to convert the conceptual model into a form that can be utilized to create an IS (e.g., a relational database)
–tool is the Relational Schema

Question 7

Physical Data Modeling

Answer 7

goal is to specify all identifying & operational characteristics of the data that will be recorded in the information system
–tools include the Data Dictionary and others

Question 8

(ERD)- Entities

Answer 8

named as singular nouns

Entity is something of interest in the environment that is described by attributes and that will have numerous instances we wish to track

Question 9

(ERD)– Attributes

Answer 9

named as singular nouns

A discrete data element
–Describes an entity (i.e., is a characteristic

Question 10

(ERD)–Relationships

Answer 10

named as verbs or verb phrases

is an association between entities

Question 11

Types of Attributes–Simple

Answer 11

at the atomic, most basic level

Question 12

Types of Attributes–Composite

Answer 12

a related group of attributes

example: Address (Street, City, State, Zip)

Question 13

Types of Attributes–Single Valued

Answer 13

only one value per entity instance (e.g., Last Name, Date Of Birth)

Question 14

Types of Attributes–Multivalued

Answer 14

• multiple values per entity instance are possible (e.g., Degree, Club, Skill)

Question 15

Types of Attributes–Derived

Answer 15

calculated, but not stored (e.g., Total)

These are only optionally shown on an ERD

Question 16

Types of Attributes–Identifier

Answer 16

• an attribute that uniquely identifies each entity instance (e.g., Social Security Number)

Question 17

candidate key

Answer 17

is any attribute that would qualify as an identifier (e.g., SSN and Employee ID)

Question 18

cardinality

Answer 18

of a relationship describes the number of instances of one entity that may be associated with one instance of another entity

specified as either one or many (many = one or more)

Question 19

optionality

Answer 19

(modality) indicates whether partici-pation in the relationship is required or not
specified as either mandatory or optional

Question 20

Two Cases When you Must Use Associative Entities–Case #1

Answer 20

If it is necessary to assign an identifier to uniquely identify each occurrence of the M:M relationship between the original entities, then an associative entity must be created.
(Entities have identifiers; relationships do not.)

Question 21

Two Cases When you Must Use Associative Entities–Case #2

Answer 21

In a ternary relationship, if the optionalities at all three entities are not identical, then an associative entity must be created. Other- wise, the ERD cannot depict the interactions between the entities without ambiguity.

Question 22

Strong Entity

Answer 22

• -exists independently of other entities
• -has its own unique identifier (shown w/single underline)
• -represented with regular rectangle symbol

Question 23

Dependent (Weak) Entity

Answer 23

• -dependent on a strong entity; cannot exist on its own
• -does not have a unique identifier, only a partial –identifier (shown w/double underline)
• -represented with rectangle symbol with lines in corners

Question 24

Identifying Relationship

Answer 24

• -links strong entities to dependent (weak) entities

- -represented with diamond symbol with lines in corners

Question 25

Two Processes to Develop Supertype/Subtypes-Generalization

Answer 25

The process of defining a more general entity type from a set of more specialized entity types
–A “bottom-up” approach

Question 26

Two Processes to Develop Supertype/Subtypes–Specialization

Answer 26

The process of defining one or more sub-types of a general entity based on distinguishing attributes or relationships
–A “top-down” approach

Question 27

Supertype

Answer 27

(example: Employee)

a generic entity that has a relationship with one or more subtypes

Question 28

Subtype

Answer 28

(example: Manager)
a subgrouping of a supertype entity that is meaningful to an organization (not just possible)
–shares all attributes of its supertype, but also has unique attributes of its own and/or :
–has relationships with other entities distinct from those of other subtypes

Question 29

Inheritance Rule

Answer 29

• -An instance of a subtype is also an instance of the supertype
• -Subtype entities inherit values of all attributes of the supertype
• –this makes it unnecessary to include the supertype’s attributes redundantly with the subtypes

Question 30

Rule Restricting the Use of Supertype/Subtypes

Answer 30

1 when there are attributes that apply to some (but not all) of the instances of an entity type

Question 31

Rule Restricting the Use of Supertype/Subtypes

Answer 31

2 .When the instances of a subtype participate in a relationship unique to that subtype

Question 32

Supertype/Subtype Relationships Rule

Answer 32

Relationships shown at the supertype level indicate that all subtypes will participate in the relationship
—(Example: “is assigned to” relationship on slide #40)

The instances of a subtype may participate in a relationship unique to that subtype; in this situation, the relationship is shown at the subtype level
—(Example: “belongs to” relationship on slide #40)

Question 33

Completeness Constraint

Answer 33

Addresses the question of whether an instance of a supertype must also be a member of at least one subtype

Question 34

Disjointness Constraint

Answer 34

Addresses the question of whether an instance of a supertype may simultaneously be a member of two (or more) subtypes

Question 35

Total Specialization Rule (Double-line notation)

Answer 35

Specifies that each entity instance of the super-type must be a member of some subtype in the relationship
–(Example: all STUDENTS are either UNDERGRADUATE or GRADUATE students)

Question 36

Partial Specialization Rule (Single-line notation)

Answer 36

Specifies that an entity instance of the super-type is allowed to not belong to any subtype (Example: FACULTY and STAFF are not the only possible types of EMPLOYEE)

Question 37

Disjoint Rule (Letter “d” notation)

Answer 37

Specifies that if an entity instance is a member of one subtype, it cannot simultaneously be a member of any other subtype (Example: all PERSONS are either MALE or FEMALE)

Question 38

Overlap Rule (Letter “o” notation)

Answer 38

Specifies that an entity instance can simultaneously be a member of two (or more) subtypes (Example: an ATHLETE can be both a RUNNER and a JUMPER)

Question 39

Subtype Discriminator

Answer 39

An attribute of the supertype whose values etermine the target subtype or subtypes
(Used to direct into which of the subtypes, if any, a new instance of the supertype should be inserted)

Disjoint – a simple attribute with alternative values to indicate the possible subtypes

Overlap – a composite attribute whose subparts pertain to different subtypes; each subpart contains a boolean value (yes or no) to indicate whether or not the instance belongs to the associated subtype