Databases

Question 1

Flat Files

Answer 1

represented by a single table

all records stored by single rows

Question 2

Flat Files - Advantages and Disadvantages

Answer 2

Advantages
Simple and easy for small applications
Users have control and access to data close to them

Disadvantages
Requires extensive programming in third-generation language (3GL)
Duplication of data leading to inaccuracies
Leads to islands of information

Question 3

Hierarchical Databases

Answer 3

Logically represented by an upside down tree

Each parent can have many children and Each child has only one parent

Question 4

Hierarchal Databases - Adv and Disadvantages

Answer 4

Advantages
Conceptual simplicity
Database security and integrity
Data independence
Efficiency

Disadvantages
Complex implementation
Difficult to manage and lack of standards
Lacks structural independence
Applications programming and use complexity
Implementation limitations

Question 5

Relational Databases

Answer 5

Perceived by user as a collection of tables for data storage
Tables are a series of row/column intersections
Tables related by sharing common entity characteristic(s)

Question 6

Relational Databases - Adv/Disadvantages

Answer 6

Adv
Require less memory for data storage
Structural independence
Improved conceptual simplicity
Easier database design, implementation, management, and use     
Powerful database management system

Disadvantages
Substantial hardware and system software overhead
Poor design and implementation is made easy
May promote “islands of information” problems

Question 7

Object Orientated Databases

Answer 7

ties related packages together

all attributes combined with an object so all info is available

Question 8

Object Orientated Database functions

Answer 8

Objects or abstractions of real-world entities are stored
Attributes describe properties and a collection of similar objects is a class
Methods represent real world actions of classes
Classes are organised in a class hierarchy

Question 9

Object Oriented Adv/Disadvantages

Answer 9

Adv
Complex data sets can be saved and retrieved quickly and easily
Object IDs are assigned automatically
Database integrity
Both structural and data independence

Disadvantages
Complex navigational data access
Steep learning curve
Object databases are not widely adopted
In some situations, the high complexity can cause performance problems

Question 10

Jargon

Answer 10

Up and Across

Question 11

Locking

Answer 11

If several users are trying to update data in a centralised database at the same time the RDBMS has to ensure that the transactions do not conflict and cause problems. If a record is only being viewed then there is no problem.

Question 12

Distributed Database

Answer 12

A distributed database is a collection of databases which are distributed over different computers on a computer network

Question 13

Distributed Database - Adv/Disadvantages

Answer 13

Adv
Improved performance due to locality of data and less users
Improved reliability as local sites can still operate with their own database if network goes down
Local autonomy as each database can have own rules and policies
Easier growth as you can expand individual parts of the database

Disadvantages
Complexity. A distributed database is more complicated to set up and maintain compared to a central database.
Security. There are many remote entry points to the system.
Data integrity. More complex to ensure data and indexes are not corrupted.
Data needs to be carefully positioned to ensure good performance
Not efficient if there is heavy interaction between branches.

Question 14

GIS

Answer 14

GIS is a System of computer software, hardware and data, and personnel to help:
Manipulate
Analyse
Present information
that is tied to a spatial location
You can also map database data to spatial locations

Question 15

GIS ADV

Answer 15

Identify Problems
Can illuminate issues that are driven by geography
Monitor change
If a picture tells a thousand words, a map tells a thousand pictures.
Manage & respond to events
Can deliver real-time situational awareness
Perform forecasting
Not just weather, but even things like traffic
Set priorities
GIS helps to set priorities based on spatial analysis.
For example analysing crime patterns, public safety officials can identify target areas and assign officers in those areas
Understand trends
helps you gain insight into data that might be missed in a spreadsheet

Question 16

CRM

Answer 16

CRM is a combination of business process and technology that seeks to understand a company’s customers from a number of perspectives including:
Who they are?
What they do?
What do they like?
Developing a personal and a professional profile about each customer can include:
Basic and historical information
Personal preferences
Trends and habits
Demographical information