Normalisation

[brooklynboy93]

Hi Guys,

Are the stages of normalisation are examinable- as in having to fill in tables to ensure they meet a specific form 1NF, 2NF or 3NF?

Or would it more just be the benefits of normalisation towards ensuring data integrity?

Cheers!!!

[MJRomeo81]

They are examinable in many ways. They can get us to look at a series of tables and then explain the normalisation that needs to take place, or as you said ask us about the benefits of normalisation.

There could even be a MC question saying something like "The difference between 1NF and 2NF is:" and then they try and trick us through wording.

In the sample VCAA uploaded in March, there was a question where we had a choice to explain one of the follwing 1NF, 2NF, 3NF.

[abzzzz]

Can someone be kind enough to explainn them XD

[MJRomeo81]

1NF ensures that only one piece of data is within a field. For example  there might be a field called "Address" and it stores your address, suburb and postcode. This is not achieving 1NF. To meet 1NF, we create more fields for the person's suburb, postcode, etc. Only ONE raw item of data is within each field. Doing so makes lookups more powerful and efficient (unless you want to parse text and rip your hair out).

2NF:
 •   Removes subsets of data that apply to multiple rows in a table and places them in separate tables
•   Creates relationships between these tables and their predecessors using foreign keys
•   Eg. storing names once in a table

Usually this happens we have a whole lot of data in one table but it really needs to go in two or more tables.

3NF:
Everything in the table must be dependant on the primary key. If it isn't it needs to be in a separate table.

These powerpoints go into much greater detail than I have:
http://vceit.com/slideshows/Database-Normalisation.ppt
http://vceit.com/slideshows/database-normalisation-forms.ppt
http://vceit.com/slideshows/database-normalisation-example.ppt

[brooklynboy93]

What MJ said & its also on page 104 of the textbook.