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Normalisation. Un-normalised. We know what data we want to store in our database Organise it into a table. Un-normalised. Un-normalised. Problem: We can’t store more than one piece of data in one field. First Normal Form. Rule: Remove all repeating groups. First Normal Form.

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Un normalised
Un-normalised

We know what data we want to store in our database

Organise it into a table



Un-normalised

Problem:

We can’t store more than one piece of data in one field


First Normal Form

Rule:

Remove all repeating groups



First Normal Form

Problems:

We have empty fields?

What happens if a student studies four courses?

It’s really complicated to read



First Normal Form

Problem:

We have redundant information


Second Normal Form

Rule:

All non-key attributes are dependant on the whole primary key

This means:

Make sure all data refers only to the primary key and only the primary key


Second Normal Form

Student

Courses


Second Normal Form

To make them talk to each other:

Enrolment


Second Normal Form

Problem:

What happens if a tutor teaches more than one course?

We get more repeating and redundancy


Third Normal Form

Rule:

No attributes are dependant on other non-key attributes

This means:

Make sure no data refers anything other than the primary key


Third Normal Form

Student

Course


Third Normal Form

Tutor

Enrolment


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