Topic 6- Databases

Question 0

What is normalisation?

Answer 0

The mathematical technique for analysing data and its staged process which improves its database design at each stage

Question 1

What is a relational database?

Answer 1

A large collection of data items stored in tables with links between them so that the data can be accessed in many different ways and by a range of different application programs

Question 2

What is data consistency?

Answer 2

Using one file to hold a central pool of data

Question 3

What is data integrity?

Answer 3

It is the correctness of the data e.g to what extent does it truthfully and accurately represent the original information

Question 4

What or data redundancy?

Answer 4

Making sure that no duplicate data is being entered into the database unnecessarily

Question 5

What is data independence?

Answer 5

Where the data and the programs used to access it are separate

Question 6

What is a flat file database?

Answer 6

It is the simplest storage system that contains any one table of data

Question 7

What are the problems with a flat file database?

Answer 7

• there is no record of a product unless it is hired out
• even if a customer has hired out a product in the past their details still need to be re entered which is time consuming
• the product details nee to be entered each time a customer hires it out which is time consuming

Question 8

What are the features of a relational database?

Answer 8

• data is held in two or more tables
• there are links between the tables
• data from any of the tables can be extracted
• greater knowledge is needed to set them up

Question 9

How is security improved in a relational database?

Answer 9

• the data is stored separately to the programs used to access it
• there is a hierarchy of passwords allowing people to only access the information necessary for them to do their job
• it is possible to restrict access to only part of the program which only uses some of the data

Question 10

What is data warehousing?

Answer 10

A huge database specifically structured for information access and reporting

Question 11

How can data warehousing be used?

Answer 11

• finding out day of the week on which a particular store sold the greatest number of a certain product in 2006
• how employee absence due to sickness varied over the last year between the Newcastle branch of a company and the Manchester branch

Question 12

What is data mining?

Answer 12

Interrogating the data in the data warehouse by drilling down into the mass of data in order to understand the data more by discovering meaningful patterns and trends

Question 13

What information can data mining produce?

Answer 13

• comparisons with competitors
• predictions for future sales
• customer buying patterns and sales patterns
• lists of customers likely to buy a certain product based on what they have bought before

Question 14

Applications of data mining?

Answer 14

• helping in the fight against terrorism
  Since 9/11 the U.S. Government has been analysing people’s travel, spending and communications habits using data mining in order to spot patterns of abnormal behaviour
• identification of customer needs
  Virgin media who supply broadband, telephone and cable TV packages use data mining to segment and target customers most likely to buy new services or upgrade those services they already have

Question 15

What are database management systems (DBMS)

Answer 15

• application packages based around the need to hold a collection of centralised and structured data for further manipulation in various ways
• all DBMS allow the user to set up their own databases and most packages are fairly flexible as to how this is done
• DBMS keep the data separately form the programs and this means that when programs are developed they are independent of how data is stored

Question 16

Features of DBMS?

Answer 16

• allow the database to be defined
• allow users to query the database
• allow data to be appended (added) deleted and edited
• allow the user to modify the structure of the database
• provide adequate security for the data held
• allow the user to import and export data

Question 17

Advantages of using a DBMS?

Answer 17

• makes people think about the data being stored and stored it in a logical and structured way
• data independence. Useful if the database programs are changed, then it is no longer necessary to reinput all the data although you usually have to convert the data using a special program
• avoids data redundancy
• because the data is held centrally, it is a cooperate resource to be used by all departments rathe than belonging to one or more departments
• data integrity maintained
• increased security
• data definitions standardised

Question 18

Disadvantages of using DBMS?

Answer 18

• learning how to use a DBMS can be difficult and take some time as they are quite complex and need a lot of knowledge about analysis and design before they can be successfully implemented
• costs for the development of a DBMS can be very high
• the whole data is stored in a central location which means that it is more vulnerable than when the data is distributed around the system so good security and disaster recovery methods should be in place