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ISDS 555 > Chapter 4 - Data Modeling and the Entity-Relationship Model > Flashcards

Chapter 4 - Data Modeling and the Entity-Relationship Model Flashcards

1
Q

What is Data?

A

Recorded facts and numbers

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2
Q

What is the Definition of Information?

A

Knowledge derived from Data
Data presented in a meaningful context
Data processed by summing, ordering, averaging, comparing, or other similar operations

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3
Q

What is a System?

A

A system is defined as a set of components that interact to achieve some purpose or goal

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4
Q

An Information System aims to produce information and has Five (5) Components. What are those Components?

A
  1. Hardware
  2. Software
  3. Data
  4. Procedures
  5. People
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5
Q

What is a Business Process?

A

A business process is a set of activities that transform input into outputs.

Inputs&raquo_space;Activities&raquo_space;Outputs

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6
Q

What is Systems Analysis and Design?

A

It is the process of creating and maintaining information systems.

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7
Q

What is a Systems Development Life Cycle (SDLC)?

A

It is an approach in systems analysis and design to develop an Information System.

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8
Q

What are the Five (5) Steps to SDLC?

A
  1. Systems Definition
  2. Requirements Analysis
  3. Component Design
  4. Implementation
  5. System Maintenance
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9
Q

What is the SDLC Process in Use? (1-4)

Step (output from the current step; input for the next step)

A

Business Process (Start; System Needed)
System Definition (Project plan)
Requirement Analysis (Approved User Requirements)
Component Design (System Design)

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10
Q

What is the SDLC Process in Use? (5-7 or 8)

Step (output from the current step; input for the next step)

A

Implementation (System)
Users (Problem or Need for Change)
System Maintenance (Back to the Top)
System Definition…

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11
Q

What does the System Definition Step include?

A

Define the IS project goals and scope
Assess the feasibility of the project
Form the project team
Plan the project

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12
Q

What does the Requirements Analysis Step include?

A

Conduct user interviews
Evaluate existing systems
Determine needed new forms/reports/queries
Identify needed new applications features and functions
Consider security and five components of an IS

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13
Q

What does the Component Design Step include?

A

Determine hardware specifications
Determine program specifications
Create the database design
Design business procedures
Create job descriptions for business personnel

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14
Q

What does the Implementation Step include?

A

Build System components
Conduct component tests
Integrate the components
Conduct integrated component tests
Convert to the new system

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15
Q

What does the System Maintenance Step include?

A

Update the system with patches, service packs, and new software releases
Record and prioritize requests for system changes of enhancements

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16
Q

What are the Three (3) Steps to the Database Development Process?

A
  1. Requirements Analysis
  2. Component Design
  3. Implementation
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17
Q

What are the Eight (1-4) Sources of Requirements for Database Applications?

A
  1. User Interviews
  2. Forms
  3. Reports
  4. Queries
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18
Q

What are the Eight (5-8) Sources of Requirements for Database Applications?

A
  1. Application programs
  2. Websites
  3. Use Cases
  4. Business rules
19
Q

What must be done when Creating a Database?

A

Data requirements must first be documented in a data model

20
Q

What is the Most Popular technique used to Create Data Models?

A

The Entity-Relationship model which was created by Peter Chen in 1976 (now interpreted as the extended entity-relationship model)

21
Q

What are the Most Important Elements of the Entity-Relationship Model? (1-4)

A

Entities
Attributes
Identifiers
Relationships

22
Q

What are Entities?

A

An entity is something that users want to track.
Entities of a certain type are grouped into an entity class
An entity instance of an entity class is the occurrence of a particular entity, such as CUSTOMER 12345

23
Q

What are Attributes?

A

They describe the entity’s characteristics
Attributes have a data type

24
Q

What are Identifiers?

A

Attributes that name or identify entity instances. Identifiers can be unique (key) or nonunique

25
Q

What are Relationships?

A

They are associations between entities. The number of entity classes in the relationship is known as the degree of the relationship. Degree 2 is binary and degree 3 is ternary.

26
Q

What is Cardinality?

A

It names and classifies relationships

27
Q

What is Maximum Cardinality vs. Minimum Cardinality?

A

Maximum Cardinality is the max number of entity instances that may participate in a relationship instance.

Minimum Cardinality is the min number of entity instances that MUST participate in a relationship instance (typically zero or one).

28
Q

What are HAS-A Relationships?

A

Each entity has a relationship to a second entity instance. (Ex. employee has a badge, badge has an employee).

29
Q

What is the IE (Information Engineering) Crow’s Foot Model?

A

It was developed by James Martin in 1990 and uses “crow’s feet” dashes to show the many sides of a relationship.

30
Q

What are the other Two Variations of the ER Model?

A

Integrated Definition 1, Extended (IDEFIX)
Unified Modeling Language (UML)

31
Q

How does the Original ER Model differ from the Crow’s Foot Model?

A

The Crow’s Foot Model uses the “crow’s feet” diagram to show both the minimum and maximum cardinality of a relationship.

32
Q

What are the Crow’s Foot Notations?

A

–I–I: Mandatory-One. Exactly One
–I–<: Mandatory-Many. One or More
–O–I: Optional-One. Zero or max one
–O–<: Optional-Many. Zero or more

33
Q

What is a Weak Entity vs. a Strong Entity?

A

A weak entity is an entity that cannot exist in the database w/o the existence of another entity.
A strong entity is any entity that is not a weak entity.

34
Q

What is an ID-Dependent Weak Entity?

A

A weak entity that cannot exist without its parent entity. ID-dependent entities have rounded corners, whereas non ones have edged corners.

35
Q

What is an Identifying Relationship?

A

The relationship between a strong and weak entity. Represented by a solid line.

36
Q

What is a Nonidentifying Relationship?

A

The relationship between a strong and weak entity if the weak entity is non-ID-dependent. It is also used between strong entities and represented by a dashed line.

37
Q

How are Weak Entities visualized?

A

Weak entities have the “tan” color in diagrams. ID-Dependent entities have rounded corners.

38
Q

What is an Associative Entity?

A

It is used whenever a pure N:M relationship cannot properly hold attributes that are describing aspects of the relationship between two entities.

39
Q

What is a Subtype? What is a Discriminator?

A

A subtype is a special case of another entity called supertype.

A discriminator is an attribute of the supertype that indicates which of the subtypes is appropriate for a given instance

40
Q

What does it mean if a Subtype is Exclusive or Inclusive?

A

If exclusive, the supertype relates to at most one subtype.
If inclusive, the supertype can relate to one or more subtypes

41
Q

What is a IS-A Relationship?

A

The relationships that connect supertypes and subtypes when the subtype is the same entity as the supertype

42
Q

What is a Recursive Relationship?

A

When an entity has a relationship with itself. (Ex. Customers who have been referred to the business by existing customers point to Customer_ID)

43
Q

After the Data Model has been created, how do you Validate the Model?

A

Most common way is to show the users and obtain their feedback
Prototyping is commonly used to validate forms and reports
A data model needs to be evaluated against all use cases

ISDS 555 (6 decks)

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