4.10.3 Database design and normalisation techniques

Question 1

What does Third Normal Form (3NF) mean?

Answer 1

Every attribute is dependent on the key only
relations contain no repeating groups of attributes
No non-key dependencies

Question 2

Why is it important that the relations in a relational database are in Third Normal Form?

Answer 2

Eliminate data inconsistency
No unnecessary repeated data / Eliminate data redundancy
Minimize or avoid data modification issues
Simplifies queries

Question 3

What is normalisation?

Answer 3

Process of restructuring a relational database using normal forms in order to reduce data redundancy and improve data integrity
By limiting a table to one purpose you reduce the number of duplicate data that is contained within your database, which helps eliminate some issues stemming from database modifications.

Question 4

Why might hashing be used to organise data in a database?

Answer 4

So that searching, adding and deleting can be done efficiently

Question 5

What makes a database un-normalised?

Answer 5

Contains a repeating group