Lecture 1

Question 1

What is an Algorithm?

Answer 1

An algorithm is any well-defined computational procedure that takes some value, or set of values, as input and produces some value or set of values as output
An algorithm can be seen as a tool for solving a well-specified computational problem.

Question 2

What is a Flat Database?

Answer 2

Stores information about a single entity

1 table

Question 3

Disadvantages of a Flat database?

Answer 3

Separation and isolation of data.
Duplication of data.
Data dependence.
Incompatibility of files.
Fixed queries and the proliferation of application of programs.
A solution to this is to use a relational database.

Question 4

What is a database?

Answer 4

A consistent store of data

Question 5

What is first normal form?

Answer 5

No repeated or similar data
Each row is unique i.e. it has a primary key
Data has to be atomic

Question 6

What is second normal form?

Answer 6

Non-key attributes must depend on every part of the primary key
The table must already be in first normal form

Question 7

What is third normal form?

Answer 7

It is already in 2NF

There are no non-key attributes that depend on another non-key attribute

Question 8

Entity relations

Answer 8

one to one-husband and wife
one to many-mother and child
many to many-actor and film

Question 9

Define a primary key?

Answer 9

A unique identifier for each record

Question 10

Define a foreign key?

Answer 10

A foreign key is an attribute that creates a join between two tables (relations).It is the attribute that is common in both tables.
It is the primary key in the first relation

Question 11

Define a secondary key?

Answer 11

A secondary key is a field in a table that can be used to access the data in different ways. It is used to search for a group of records.

Question 12

What is a DBMS?

Answer 12

a database management system defines, creates and maintains a database. The DBMS also allows controlled access to data in the database
Includes a data dictionary which is a file of descriptions of the data and structure

Question 13

Views of data: Internal level

Answer 13

This is the view of the entire database store in the system. It is hidden from the user by the DBMS.

Question 14

Views of data: Conceptual level

Answer 14

Gives a single usable view of all the data on the database

Question 15

Views of data: External level

Answer 15

Where data is arranged according to user requirements and rights. Different users will get different views of the data.