Topic 2: Data Models

Question 1

define data model

Answer 1

representative of complex real-world data structure via graphical representation

Question 2

define data modeling

Answer 2

progressive process of creating a specific data model to determine problem domain

Question 3

importance of data modeling

Answer 3

• communication tool
• overall view for creating a good database
• organised data

Question 4

4 data model basic building blocks

Answer 4

• Entity: category of the data
• attribute: characteristics of entity
• relationship: association among entities
• constraint: restriction on data

Question 5

5 types of data model

Answer 5

• hierarchical model
• network model
• relational model
• entity relationship model
• object-oriented

Question 6

3 data abstraction level

Answer 6

• external: end-user view
• conceptual: global view
• internal: DBMS view
• physical: way of data storage

Question 7

4 elements in external schema

Answer 7

• entities
• relationships
• processes
• constraints

Question 8

NoSQL

Answer 8

• to process large-scale database
• support distributed architecture
• support large amount of data
• provide high availability, high scalability, and fault tolerance
• focus on performance rather than transaction consistency

Question 9

what is map reduce in Hadoop cluster

Answer 9

Map: filter and sort the data
reduce: summarise the data

Question 10

define hierarchical model

Answer 10

basic logical structure represent by upside down ‘tree’
- contain levels and segments

Question 11

define network model

Answer 11

to represent complex data relationships more effectively than the hierarchical model

Question 12

define relational model

Answer 12

create relational table stores collection of related entities

Question 13

advantages of relational model

Answer 13

• hide complexity from user by isolating user from physical level details
• promote structure independence via independent table
• improve conceptual simplicity
• ad hoc query

Question 14

Define entity relationship model

Answer 14

Graphical representation of entities and their relationships in a database structure

Question 15

advantages of ERD

Answer 15

• graphical representation
• show interrelationship among entities
• show major entity in diagram

Question 16

define object oriented model

Answer 16

Data and relationships are contained in a single structure known as an object

Question 17

advantages of OOM

Answer 17

• data integrity
• visual representation
• semantic content