Chapter 5 - Databases

Question 1

Database

Answer 1

Persistent (saved on secondary storage) organised store of data

Question 2

Data integrity

Answer 2

Data reflecting reality

Question 3

Validation

Answer 3

The process of checking data through software when it is input

Question 4

Verification

Answer 4

Checking that the data entered is correct with duplicate file

Question 5

Data matching

Answer 5

Compares different databases to look for particular relationships

Question 6

Data mining

Answer 6

Looks in many different unrelated databases

Question 7

Flat file database

Answer 7

Just rows (records) and columns (fields) - only 1 table

Question 8

Data redundancy

Answer 8

Unnecessarily storing data in several places (repetition)

Question 9

Relational databases

Answer 9

Stores data in separate tables which are linked on key fields

Question 10

Entity

Answer 10

Something in real life about which data can be stored

Question 11

DBMS

Answer 11

Database Management System is software that creates and manages a database and separates data from applications to minimise data redundancy

Question 12

Transactions

Answer 12

A change in a database - must not damage data integrity

Question 13

Record locking

Answer 13

Allows only one person to edit data at one time

Question 14

Primary key

Answer 14

Unique identifier of a record which can be linked to a foreign key from another table

Question 15

Forms

Answer 15

Provide a user friendly interface for data input or output

Question 16

Reports

Answer 16

Physical outputs from a database

Question 17

Queries

Answer 17

Used to extract data (using either a graphical interface or SQL (structured query language))

Question 18

Modules

Answer 18

Units of software that take care of a particular function

Question 19

What do databases need to be? (4)

Answer 19

1) Accurate
2) Up to date
3) Available
4) Protected

Question 20

What do databases need to be protected against? (5)

Answer 20

1) Errors
2) Loss
3) Insufficient data
4) Inconsistencies
5) Unauthorised access

Question 21

How can data be lost? (3)

Answer 21

1) Catastrophes e.g. flood
2) Accidental deletion
3) Malicious action

Question 22

How can database problems be avoided? (4)

Answer 22

1) Validation
2) Frequent back ups
3) Locking action
4) Access levels

Question 23

What do most people need to do to a database?

Answer 23

Create
Read
Update
Delete

Question 24

What are the disadvantages of flat file databases? (2)

Answer 24

1) Very limited

2) Data redundancy - inconsistent updates

Question 25

What does a DBMS do? (4)

Answer 25

1) Creates database applications
2) Protects data
3) Runs queries
4) Keeps data consistent and accurate

Question 26

Why does data need to separated from applications? (4)

Answer 26

1) Programmers do not have to worry about damaging data
2) Applications can be written without restructuring data
3) Data easily shared between applications
4) Only one copy of data - no redundancy

Question 27

What are the main features of a DBMS? (7)

Answer 27

1) Record locking
2) Creating tables
3) Graphs
4) Queries
5) Validation
6) Security
7) Automatic backups

Question 28

Why are data types used?

Answer 28

Makes it easier for software to validate and process data, and decisions about space allocation can be made

Question 29

What is a range check?

Answer 29

Checking if value entered fits into pre-determined range, data falls between two extreme values

Question 30

What is a check digit?

Answer 30

Extra digit added to data produced by an algorithm