Exam 1-Chapter 2

Question 1

Model

Answer 1

An abstraction of a real-world object or event; useful in understanding complexities of the real world environment

Question 2

Data Models

Answer 2

Relatively simple representations of complex real-world data structures (often graphical); data modeling is iterative and progressive)

Question 3

Importance of Data Models

Answer 3

Facilitate interaction among the designer, the applications programmer, and the end user
End users have different views and needs for data
Data model organizes data for various users
Data model is an abstraction (cannot draw required data out of the data model)

Question 4

Entity

Answer 4

Anything about which data are to be collected and stored

Question 5

Attribute

Answer 5

Describes an association among entities
One-to-many (1:M) relationship
Many-to-many (M:N or M:M) relationship
One-to-one (1:1) relationship

Question 6

Constraint

Answer 6

A restriction placed on the data

Question 7

Business Rules

Answer 7

Descriptions of policies, procedures, or principles within a specific organization (apply to any organization that stores and used data to generate information); Description of operations to create/enforce actions within an organization’s environment (must be in writing and kept up to date;must be easy to understand and widely disseminated);describe characteristics of data as viewed by the company

Question 8

Sources of Business Rules

Answer 8

Company managers
Policy makers
department managers
Written documentation (procedures;standards; operations manuals)
Direct interviews with end users

Question 9

Importance of Documenting Business Rules

Answer 9

• Standardize company’s views of data
• Communications tool between users and designers
• Allow designer to understand the nature, role, and scope of data
• Allow designer to understand business processes
• Allow designer to understand business processes
• Allow designer to develop appropriate relationship participation rules and constraints

Question 10

The Hierarchical Model

Answer 10

The hierarchical model was developed in the 1960s to manage large amounts of data for manufacturing projects
Basic logical structure is represented by an upside-down “tree” with levels or segments
Higher layer=parent
Lower layer=child
1:1, 1:M

Question 11

Network Model

Answer 11

The network model was created to represent complex data relationships more effectively than the hierarchical model (improves database performance)
Network database=collection of records in 1:M and M:M relationships

Question 12

Owner

Answer 12

Equivalent to the hierarchical model’s parent

Question 13

Member

Answer 13

Equivalent to the hierarchical model’s child

Question 14

Schema

Answer 14

Conceptual organization of entire database as viewed by the database administrator

Question 15

Subschema

Answer 15

Database portion “seen” by the application programs

Question 16

Data Management Language (DML)

Answer 16

Defines the environment in which data can be managed

Question 17

Data Definition Language (DDL)

Answer 17

Enables the administrator to define the schema components

Question 18

Disadvantages of the Network Model

Answer 18

Became too cumbersome for larger, more complex data sets
Lack of ad hoc query capability placed burden on programmers to generate code for reports
Structural change in the database could produce havoc in all application programs

Question 19

Relational Database Management System (RDBMS)

Answer 19

Hides complexity from the user by managing all the physical details and allowing the user to work at the logical level
How the data is physically stored in the database is of no concern to the user or the designer
Relational table stores collection of related entities
Tables are related through common attributes

Question 20

Relational Diagram

Answer 20

Representation of entities, attributes, and relationships

Question 21

Entity Relationship Model

Answer 21

Graphical representation of entities and their relationships in a database structure
Entity is represented in ERD by a rectangle
Mapped to a relational type

Question 22

Entity Relationship Diagram (ERD)

Answer 22

Uses graphic representations to model database components

Entity is mapped to a relational table

Question 23

Chen Notation

Answer 23

Relationships are represented by a diamond with the relationship name written inside it
Connectivities written next to entity boxes

Question 24

Crow’s Foot Notation

Answer 24

Connectivities represented by symbols

Question 25

Object-Oriented (OO) Model

Answer 25

OODM (Object-Oriented Data Model) is the basis for OODBMS
Both data and relationships are contained in a single structure known as an object
An object also contains all operations that can be performed on it

Question 26

Classes

Answer 26

Objects that share similar characteristics (attributes and methods) 
Organized in a class hierarchy

Question 27

Inheritance

Answer 27

Object inherits methods and attributes or parent class

Question 28

Unified Modeling Language (UML)

Answer 28

Based on OO concepts that describe diagrams and symbols (used to graphically model a system, UML class diagrams used to represent data and relationships

Question 29

Extended Relational Data Model (ERDM)

Answer 29

Semantic data model developed in response to increasing complexity of applications
Includes many of OO model’s best features
Often described as an object/relational database management system (O/RDBMS)
Primarily geared to business applications

Question 30

Extensible Markup Language (XML)

Answer 30

The Internet revolution created the potential to exchange critical business information
Emerged as the de facto standard
Current databases support XML (XML: the standard protocol for data exchange among systems and Internet services

Question 31

Big Data

Answer 31

• Find new and better ways to manage large amounts of Web-generated data and derive business insight from it
• Simultaneously provides high performance and scalability at a reasonable cost
• Relational approach does not always match the needs of organizations with Big Data Challenges

Question 32

NoSQL Databases

Answer 32

• Not based on the relational model, hence the name NoSQL
• Supports distributed database architectures
• Provides high scalability, high availability, and fault tolerance
• Supports very large amounts of sparse data (number of attributes is very large; number of actual data instances is low)
• Geared toward performance rather than transaction consistency

Question 33

External Schema

Answer 33

Specific representation of an external view, Includes:

• Entities
• Relationships
• Processes
• Constraints

Question 34

The Conceptual Model

Answer 34

Represents global view of the entire database
All external views integrated into single global view: conceptual model or schema
-ERD graphically represents the conceptual schema (logical model)
-Provides a relatively easily understood macro level view of data environment
-Independent of both software and hardware

Question 35

THey Physical Model

Answer 35

• Operates at lowest level of abstraction
• Requires the definition of physical storage and data access methods
• Physical independence: when changes in physical model do not affect internal model