Week 1

Question 1

What is data?

Answer 1

Data is raw facts; building blocks of information. Also known as unprocessed information.

Question 2

What is information?

Answer 2

Information is data that has been processed to reveal meaning.

Question 3

What is a database?

Answer 3

A database (DB) is a managed (specialised and integrated) collection of associated data stored in a computer system, it is:
- Shared by multiple users
- Protected with security measures
- Stored with controlled redundancy
- Can be retrieved quickly

Question 4

What is a DBMS?

Answer 4

A Database Management System (DBMS) is a program or a collection of programs through which users interact with a database.

Question 5

What are the roles of the DBMS?

Answer 5

The roles of the DBMS are:

• Intermediary between the user and the database
• Enables data to be shared
• Presents the end user with an integrated view of the data
• Receives and translates application requests into operations required to fulfil the requests
• Hides database’s internal complexity from the application programs and users

Question 6

What is the importance of DB Design?

Answer 6

A poorly designed DB can:

• generate errors
• lead to bad decisions
• lead to failure of organization

A well-designed DB:

• facilitates data management (e.g. avoid redundant data)
• generates accurate and valuable information
• helps decision making
• leads to business success

Question 7

What is redundancy?

Answer 7

Redundancy is the duplication of data or the storing of the same data in more than one place.

Question 8

What are some problems with redundancy?

Answer 8

Some problems with redundancy are:

• Data becomes inaccurate
  If a certain field (e.g. address) occurs in the database several times errors will occur if all occurrences of the data are not updated when the field value changes
• Extra data entry time
  Greater data entry time because the same data has to be entered multiple times.
• Extra data storage
  This is a minor problem as storage is so cheap these days.

Question 9

What are the parts of a computer data file?

Answer 9

The parts of a computer data file are:

• File:
  Collection of related records
• Field:
  Group of characters with specific meaning
• Record:
  Logically connected fields that describe a person, place, or thing
• Data:
  Raw Facts

Question 10

What are some problems with file systems for data processing?

Answer 10

Some problems with file systems are:

• Lengthy development times
• Difficulty of getting quick answers
• Complex system administration
• Lack of security and limited data sharing
• Extensive programming

Question 11

What are the four main problems with file systems for data processing?

Answer 11

The four main problems with file systems for data processing are:

• Structural Dependence
• Data Redundancy
• Data Dependence
• Data Anomalies

Question 12

What is structural dependence?

Answer 12

Structural dependence is where access to a file depends on its own structure, e.g. the order of the fields. All file system programs are modified to conform to a new file structure

Question 13

What is data redundancy?

Answer 13

Data redundancy is where different and conflicting versions of the same data appear in different places unnecessarily. This results in data inconsistency and poor data security

Question 14

What is data dependence?

Answer 14

Data dependence is where changes in the data storage characteristics (the length and data type of fields) affect the application program’s ability to access the data

Question 15

What are data anomalies?

Answer 15

Data anomalies develop when required changes in redundant data are not made successfully. Anomalies can be created through updates of data, insertion of new data, and deletion of data.

Question 16

What are the types of database by users?

Answer 16

• Single user DB: Supports only one user at a time
• Multi user DB: Supports multiple users at the same time
  
  • Workgroup DB
    Supports a small group of users or a
    single department
  • Enterprise DB
    Supports a large group of users or an
    entire organisation

Question 17

What are the types of database by location?

Answer 17

• Centralised DB:
  Supports data located at a single site
• Distributed DB:
  Supports data distributed across several
  sites
• Cloud DB:
  Created and maintained using cloud
  data services that provide defined
  performance measures for the database

Question 18

What are the types of database by use?

Answer 18

• Transactional (or Operational) DB:
  Supports a company’s day to day
  operations
• Analytical (Data warehouse) DB:
  Stores data used to generate
  information required to make tactical or
  strategic decisions. Often used to store
  historical data. Structure is quite
  different.

Question 19

What are the 5 main parts of a database system?

Answer 19

• Hardware
• Software
  - Operating system software
  - DBMS software
  - Application programs and utility
  software
• People
• Procedures
• Data

Question 20

What are the advantages of database systems?

Answer 20

The advantages of a database system include:

• Improved data sharing
• Better data integration and security
• Minimized data inconsistency
• Improved decision making
• Increased end-user productivity

Question 21

What is data independence?

Answer 21

Data independence is where changes in the structure of the database do not affect the applications functionality.

Question 22

What is structural independence?

Answer 22

Structural independence is where access to a file does not depend on its own structure. How the data is physically stored will not affect the functionality of the application.

Question 23

What is data integrity?

Answer 23

Data integrity is ensuring that each row of a table is uniquely identified so that data can be retrieved separately