Databases

Question 1

What is data?

What is created whern you process data?

Answer 1

Data is building blocks of information

Information is created as a result of processing data

Question 2

Provide a description of a database

Answer 2

A database is a shared integrated computer structure that stores end user data

Question 3

What is a RDMS? What does it do?

Answer 3

Relational Database Management System

An RDMS helps to manage database content

Changes user commands into queries

Question 4

What is a relational database?

Answer 4

Data is stroed once centrally. In a table(Relation)

A realtion is an association of many things

Question 5

Attributes & tuples make a relation

Define an attribute:

Define a tuple:

Answer 5

Attributes are properties(column)

Tuples are occurences(rows)

Question 6

Define OLTP

Define OLAP

Answer 6

Online transaction processing- Fast querying, processing, maintaining data integrity in multi access enviroments. Effectnivness measured by transactions per second

On line analytical processing- Low volume of transactions measured by response time

Question 7

List advanatages of a Relational Dabatbase

List disadvantages of a relational Database

Answer 7

Advantages

• Sound mathematical theory
• No repetition of data
• Declarative language for query

Disadvantages

• Requires memory/processing power
• Requires data modelling

Question 8

What is data redunancy? What does it cause?

What are the three anomalies?

Answer 8

Inslands of information stored in different georgraphical locations which causes data inconsistency, different versions of the same data existing in different places

Update anomalie- Locatig of depart changefd then many records have to be updates

Insertion anomalie- How do you create a department without an employee?

Deletion anomalie- Delete the last and only employee in a department without deleting the department