Chapter 2

Question 1

What are data models?

Answer 1

Data models are simple graphical representations of complex real-world structures.

Question 2

What is the importance of data models?

Answer 2

facilitate interaction among the designer, the applications programmer and end-user.
Organizes data for various users.

Question 3

What is an entity?

Answer 3

Anything about data that is about to be stored and collected.

Question 4

What is an attribute?

Answer 4

A characteristic of an entity.

Question 5

What is a relationship?

Answer 5

An association among entities.

Question 6

What are the types of relationships?

Answer 6

One-to-many (1:) relationship
Many-to-many (:*) relationship
One-to-one (1:1) relationship

Question 7

What is a constraint?

Answer 7

It is a restriction placed on data.

Question 8

List the sources of business rules.

Answer 8

Company managers
Policy-makers
Department managers
Written Documentation
Direct Interviews with end-users

Question 9

What are business rules?

Answer 9

Brief and precise policies within a specific organization that stores and uses data to generate information.

Question 10

What are the types of data models?

Answer 10

Hierarchical
Network
Relational
Entity relationship
Object oriented (OO)

Question 11

Briefly describe the relational model in detail.

Answer 11

Developed by Codd(IBM) in 1970
Ingenious but impractical in 1970
Conceptually simple
Computers back then lacked power to implement relational model
Microcomputers today can run relational database software.

Question 12

Know the evolution of data models.

Answer 12

AYT BET.

Question 13

How many generations of data models are there?

Answer 13

6 with the emerging models like NoSQL.

Question 14

Give some examples of Hierarchical and Network Databases.

Answer 14

IMS, ADABAS, IDS-II

Question 15

Give some characteristics of the Hierarchical and Network Databases.

Answer 15

They used:
Early database systems
Navigational Access

Question 16

Give some examples of a Relational Database.

Answer 16

DB2
Oracle
MySQL
MySQL Server

Question 16

Give some characteristics of the Relational Database.

Answer 16

It is Conceptually simple
It Supports ER Modelling

Question 17

Give some examples of an Object-oriented Database.

Answer 17

Versant.
DB2 UDB
DB
Oracle 11g

Question 17

Give some characteristics of the Object-oriented Database.

Answer 17

Supports object data types.
Web databases become common.
Supports Star Schema for data warehousing.

Question 18

What is the advantage of the RDBMS?

Answer 18

It can hide the complexities of the relational model from the user.

Question 19

What is a relational diagram?

Answer 19

It is a representation of relational database’s entities, attributes within those entities, and the relationships between those entities.

Question 20

What role does SQL play in relational databases?

Answer 20

Allows user to specify what must be done without specifying how it must be done.

Question 21

What does an SQL-based relational database consist of?

Answer 21

A User Interface
Set of tables in the database
SQL Engine

Question 22

What is an Entity Relationship (ER) Model defined as?

Answer 22

It is a graphical representation of entities and their relationships in a database structure.
Introduced by Chen in 1976

Question 23

What is Big Data?

Answer 23

It is managing large web data for business insights, performance, and scalability at a good cost.