Data Normalisation

Question 1

Explain

How do you normalise to first normal form?

(1NF)

Answer 1

• Ensure there are no repeated columns
• Ensure cell atomicity

Question 2

Recall

How do you convert data to a relation?

Answer 2

Convert it to first normal form. (same criteria)

Question 3

Define

Atomicity of database cells

Answer 3

Cells only contain a single piece of data

(i.e. not multiple pieces of data separated using commas)

Question 4

Explain

How do you normalise to second normal form?

(2NF)

Answer 4

• Have no partial dependencies

(if none are present, it’s already in 2NF.)

Prerequisite: data is in 1NF.

Question 5

Define

Partial Dependency

Answer 5

When a non-key attribute depends on only part of a composite key, as opposed to the whole composite key.

Question 6

Explain

How do you normalise to third normal form?

(3NF)

Answer 6

• Have no transitive dependencies

Prerequisite: data is in 2NF.

Question 7

Define

Transitive Dependency

Answer 7

when a non-key field is dependent on a field other than the primary key