SLR 10

Question 1

What does organising data in a database allow for?

Answer 1

Adding, Modification, Deletion, Searching

Question 2

What are electronic databases good for?

Answer 2

Makes it easier to backup data and save copies

Can be accessed by multiple people at a time and from many different locations

Question 3

How is data stored in a table

Answer 3

Entities/files are stored in records (rows/tuples) and fields (columns/attributes)

Question 4

What is a flat tile database?

Answer 4

A simple representation of data on a table

Question 5

Why are large flat tile databases inefficient?

Answer 5

If they end up too large they end up inefficient as they are waste space, making them slow and hard to maintain

Question 6

What is a relational database?

Answer 6

A database which is split into multiple tables which are all linked together. There should be one common field in all tables for the link to work

Question 7

What is a foreign key?

Answer 7

A column which is linked to another column in a linked table

Question 8

What are the 3 types of relationships?

Answer 8

One-to-one
One-to-many
Many-to-many

Question 9

How can a database be made useful?

Answer 9

Allowing it to query to quickly retrieve information

This is done by keeping an index of primary keys

Question 10

What are the methods of capturing data?

Answer 10

Capturing
Selecting
Managing
Exchanging

Question 11

What is a paper based form?

Answer 11

A physical sheet of paper you can write on, which can be scanned in order to collect data. This is done using Optical Character Recognition (OCR)

Question 12

What is Optical Character Recognition (OCR)?

Answer 12

Scans an image for text symbols into a machine-readable format

Question 13

What is Optical Mark Recognition (OMR)?

Answer 13

Used to scan multiple choice tests and lottery tickets, helping reduce human error

Question 14

What is Structured Query Language (SQL) used for?

Answer 14

To retrieve data with the following commands:
SELECT
FROM
WHERE

It is developed with Query By Example (QBE) to create statements which are executed against the database to complete the above tasks

Question 15

What can SQL AND QBE do?

Answer 15

Specify tables
Specify fields
Specify criteria
Specify output sorting
Using boolean expressions such as NOT, OR, NOT

Question 16

How are tables modified?

Answer 16

Using Database Manipulation Language (DML) these can be used:
UPDATE
DELETE
INSERT

Question 17

What does ADBMS do?

Answer 17

Prevents the creating of duplicate private keys
Enforcing validation rules
Provides secure access
Provides encryption
Provides program data independence
Manages multiple users

Question 18

What is XML and JSON?

Answer 18

They are human-readable and are open formats for structuring data
They’re common standards for storing and transporting data

Question 19

How can data be exchanged?

Answer 19

Memory strikes
Optical media
Removable hard disks
Emails
Paper based forms

Question 20

What is an Electronic Data Interchange (EDI)

Answer 20

A protocol which faciliates the exchange of data

Question 21

What are the 3 types of standard form?

Answer 21

1NF, 2NF, 3NF

Question 22

What rules need to be followed to get 1NF?

Answer 22

1. All field names must be unique
2. Values in fields should be from the same domain
3. Values in fields should be atomic
4. No two records can be identical
5. Each table needs a primary key

Question 23

What rules need to be followed to get 2NF?

Answer 23

1. The data is already in 1NF
2. Any partial independencies must be removed

Question 24

What is a partial independency?

Answer 24

Occurs when one primary key determines another attribute

Question 25

What is a dependency?

Answer 25

When one field relies on another field

Question 26

What rules are need to be followed to get 3NF?

Answer 26

1. The data is in 2NF
2. Any transitive dependencies must be removed

Question 27

What is a non-dependency key?

Answer 27

A value of a field which requires the value of another field that isn’t a part of the primary key

To remove this, get rid of unnecessary data and fields

Question 28

What is a transitive dependency?

Answer 28

When an unrelated column is dependent on another unrelated column

Question 29

What does atomic mean in CS?

Answer 29

A single item of data

Question 30

What does SQL let you do?

Answer 30

Query Data
Manipulate data
Define data
Control data access

Question 31

What SQL commands must you know?

Answer 31

SELECT
FROM
WHERE
LIKE
AND
OR
DELETE
INSERT
DROP
JOIN

Look in notes for examples

Question 32

What is data integrity and what is it needed for?

Answer 32

Keeping a database consistent

This is needed so the database is always updated for everybody who access is

Definition: “The maintenance and consistency of data in a data stored. The data must relfect the reality of what it represents”

Question 33

What is transactional processing?

Answer 33

Any information processing that is divided into individual operations called transactions

Each transaction needs to be complete as for everybody else it’ll never be partially complete

Question 34

What is CRUD?

Answer 34

The commands:
CREATE (INSERT/CREATE)
READ (SELECT)
UPDATE
DELETE

Question 35

What ensures data integrity?

Answer 35

Atomicity
Consistency
Isolation
Durability

Question 36

What does Atomicity mean?

Answer 36

Means a change to a database is either completely performed or not at all

Question 37

What does Consistency mean?

Answer 37

Any change in a database must retain the overall state, so if someone sends another money, they lose it and the other gains it

Question 38

What does Isolation mean?

Answer 38

Means a transaction can’t be interrupted by another interruption

The current data used in the transaction is made so it can’t be accessed

Question 39

What does Durability mean?

Answer 39

Means any change made to a database can’t be lost due to a system failure.

This is done by writing the effect of a transaction onto a non-volatile secondary storage so it can never be lost