MIS 3301 - Chapter 8 Quiz

Briefly identify four important business rules for supertype/subtype relationships.

-Total Specialization Rule - Every supertype instance must belong to at least one subtype. -Partial Specialization Rule - A supertype instance may or may not belong to a subtype. -Disjoint Rule - A supertype instance can belong to only one subtype. -Overlap Rule - A supertype instance can belong to multiple subtypes.

Define domains for the following attributes: Account number.

A unique numeric (or alphanumeric) identifier, typically a fixed-length string (e.g., 8-12 digits), that must be non-null and non-negative.

A(n) ________ is a person, place, object, event, or concept in the user environment about which the organization wishes to maintain data.

Entity

An entity type that associates the instances of only one type and contains attributes that are peculiar to the relationship between those entity instances.

False

Each entity type in an E-R model is given a ________ because it represents a class or set, it is singular.

Name

Supertype

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

A(n) ________ is an attribute that must have a value for every entity instance.

Required attribute

Optional attribute

an attribute that may not have a value for every entity instance

Entity instance

single occurrence of an entity type

Business rules

specifications that preserve the integrity of the logical data model

A class that can have direct instances (e.g., Outpatient or Resident Patient) is called a(n) ________ class.

Concrete

A primary key is an attribute (or combination of attributes) that uniquely identifies each instance of an entity type.

False

Conceptual data modeling is not done in parallel with other requirements analysis and structuring steps during systems analysis.

False

Projects with purchased models take less time and cost more because the initial discovery steps are no longer necessary, leaving only iterative tailoring and refinement to the local situation.

False

The ________ is a logical grouping of objects that have the same (or similar) attributes, relationships, and behaviors; also called class.

Object class

What unique characteristic(s) distinguish(es) each object from other objects of the same type?

Primary key

Which business rule specifies rules concerning the relationships between entity types?

Referential integrity constraints

Mandatory vs. Optional Cardinalities

Specifies whether an instance must exist or can be absent in the relationship

A ________ is an entity type that is meaningful to the organization and that shares common attributes or relationships distinct from other sub-groupings.

Subtype

Top-down approach

The data model is created from a strong understanding of the business's goals, processes, and rules. Analysts work closely with stakeholders to define entities and relationships based on how the business operates.

Bottom-up approach

The data model is developed by analyzing existing documents, reports, forms, and system specifications. It focuses on identifying data elements that already exist in the system and organizing them into a model.

The ________ rule specifies that each entity instance of the super-type must be a member of some subtype of the relationship.

Total specialization

An association usually means that an event has occurred or that some natural linkage exists between entity instances.

True

An entity has its own identity that distinguishes it from each other entity.

True

An identifier is a candidate key that has been selected to be used as the unique characteristic for an entity type.

True

Domain definitions typically specify some (or all) of the following characteristics of attributes: data type, length, format, range, allowable values, meaning, uniqueness, and null support (whether an attribute value may or may not be null).

True

The other deliverable from conceptual data modeling is a full set of entries about data objects that will be stored in the project dictionary, repository, or data modeling software.

True

The technique of hiding the internal implementation details of an object from its external view is known as encapsulation.

True

Identifier

a candidate key that has been selected as the unique, identifying characteristic for an entity type

Conceptual data modeling

a detailed model that captures the overall structure of data in an organization

Entity-Relationship data model

a detailed, logical representation of the entities, associations and data elements for an organization or business area

Entity-relationship diagram

a graphical representation of an E-R model

Attribute

a named property or characteristic of an entity that is of interest to the organization

Entity

a person, place, object, event or concept in the user environment about which data is to be maintained

Binary relationship

a relationship between instances of two entity types (Most common type of relationship encountered in data modeling)

Repeating group

a set of two or more multivalued attributes that are logically related

Ternary relationship

a simultaneous relationship among instances of three entity types

Subtype

a subgrouping of the entities in an entity type

Triggering operations

other business rules that protect the validity of attribute values

Referential integrity constraints

rules governing relationships between entity types

What are the rules for naming and defining attributes?

Naming Rules for Attributes: -Be descriptive an Clear -Use Singular Nouns -Use Consistent Naming Conventions -Avoid Reserved Words -No special characters or spaces -Be unique within an entity Defining Rules for Attributes -Specify Data Type -Define Length or Size -Allowable values or domain -nullability meaning and purpose

A common mistake many people make when they are just learning to draw E-R diagrams, especially if they already know how to do data flow diagramming, is to confuse data entities with ________ and relationships with data flows.

Sinks

Unary relationship

a relationship between the instances of one entity type (Also called a recursive relationship)

Secondary Key

an attribute (or combination of attributes) used for data retrieval or sorting, but not for uniquely identifying records.

Composite attribute

an attribute that has meaningful component parts (A typical example of a composite attribute is a person's address, which is composed of atomic attributes, such as City, Zip, and Street.)

Multivalued attribute

an attribute that may take on more than one value for each entity instance

Required attribute

an attribute that must have a value for every entity instance

Derived attribute

an attribute whose value can be computed from related attribute values

Entity type

collection of entities that share common properties or characteristics

Domain

constraints on valid values for attributes

Overlap rule

specifies that an entity instance can simultaneously be a member of two (or more) subtypes.

Partial specialization

specifies that an entity instance of the supertype does not have to be long to any subtype, and may or may not be an instance of one of the subtypes.

Total specialization

specifies that each entity instance of the supertype must be a member of some subtype in the relationship.

Disjoint rule

specifies that if an entity instance of the supertype is a member of one subtype, it cannot simultaneously be a member of any other subtype.

Composite Key

A primary key that consists of more than one attribute.

Entity integrity

unique, non-null identifiers

Primary Key

A field (or group of fields) that uniquely identifies a given entity in a table

Entity Relationship Diagram

A methodology for documenting databases illustrating the relationship between various entities in the database.

List and explain the following key data modeling terms: entity, attribute, relationship, degree, cardinality, and associative entity.

Entity - a thing, person, place, event, or concept about which data is collected and stored. Attribute - a characteristic or property of an entity. Relationship - shows two or more entities are connected. Degree - number of entities involved in a relationship: Unary, Binary, Ternary Cardinality - specifies the number of instances of one entity that can or must be associated with instance of another. (1:1), (1:M), (M:N) Associative Entity - used to convert a many to many relationship into two one to many relationships.

The most common format used for data modeling is ________ diagramming.

Entity-relationship

Relationship

an association between the instances of one or more entity types that is of interest to the organization

Candidate key

an attribute (or combination of attributes) that uniquely identifies each instance of an entity type

Degree

the number of entity types that participate in a relationship

Cardinality

the number of instances of entity B that can (or must) be associated with each instance of entity A

A(n) ________ is an attribute that has meaningful component parts.

Composite attribute

Which benefit of purchased data models refers to the fact that they are very general, covering almost all options employed by the associated functional area or industry?

Consistent and complete

The disjoint rule specifies that if an entity instance of the supertype is a member of one subtype, it can simultaneously be a member of any other subtype.

False