[Year 12 IT Apps] NINE mark question??

Wed Nov 14 14:03:01 EST 2012

I worst part of the question 9 is that "explain how each normal form (1-3) ensures the integrity of data"

I taught my kids what each of the normal forms 1 to 3 are, like you did. I even SACed it in U3O2 and made it a focus this year (thankfully)

BUT

To explain how each of the normal forms ensures integrity individually.... I have a Bachelor of Applied Computing (having done database units) and I don't know how to explain that, the way I think VCAA is asking.....

I did joke with my students coming out of the exam that obviously VCAA said an 8 mark question that 25% got 0 on wasn't hard enough. Let's give than 2 pages and a 9 marker.... AND a 6 mark normalisation question (with explain each form.....)

Ta

Ben Hines

Ben Hines
Mathematics and ICT Teacher
Senior Campus
(03)5241 1577

[Christian College Geelong]

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From: itapps-bounces at edulists.com.au [mailto:itapps-bounces at edulists.com.au] On Behalf Of Mark Scott
Sent: Wednesday, 14 November 2012 10:46 AM
To: Year 12 IT Applications Teachers' Mailing List
Subject: Re: [Year 12 IT Apps] NINE mark question??

This is the definition of the Normalisation process that I have been using

First Normal Form (1NF)
First normal form (1NF) sets the very basic rules for an organized database:
*         Eliminate duplicative columns<http://databases.about.com/library/glossary/bldef-column.htm> from the same table.
*         Create separate tables for each group of related data and identify each row<http://databases.about.com/library/glossary/bldef-row.htm> with a unique column or set of columns (the primary key<http://databases.about.com/library/glossary/bldef-primarykey.htm>).
Second Normal Form (2NF)
Second normal form (2NF) further addresses the concept of removing duplicative data:
*      Meet all the requirements of the first normal form.
*      Remove subsets of data that apply to multiple rows of a table and place them in separate tables.
*      Create relationships between these new tables and their predecessors through the use of foreign keys<http://databases.about.com/library/glossary/bldef-foreignkey.htm>.
Third Normal Form (3NF)
Third normal form (3NF) goes one large step further:
*      Meet all the requirements of the second normal form.
*      Remove columns that are not dependent<http://databases.about.com/od/specificproducts/a/Database-Dependency.htm> upon the primary key.

In terms of Q6

1NF as per Peter's example

2NF Split into three tables

3NF Get rid of the calculated field

It is a bit annoying that VCAA couldn't prepare us for this sort of question and indeed wouldn't even give us a definition of the process.

thanks
Mark Scott
Luther College

From: itapps-bounces at edulists.com.au<mailto:itapps-bounces at edulists.com.au> [mailto:itapps-bounces at edulists.com.au] On Behalf Of Peter Langham
Sent: Wednesday, 14 November 2012 10:05 AM
To: Year 12 IT Applications Teachers' Mailing List
Subject: Re: [Year 12 IT Apps] NINE mark question??

Here's my attempt at the normalisation question

1NF - No lists of data in any cell.
Divide the data in any of the memberName, memberAddress, driverName fields.
memberAddress becomes: memberAddress becomes memberAddress and memberPostcode
E.g.
memberAddress : 2 Hill St
memberSuburb : Richmond
This allows for more specific queries. E.g. Filtering data by Suburb.

2NF - each non-key field must be fully dependent on the key
yearsWorked is dependent on driverName. Make a seperate table where driverName is the Primary Key and it is a Foreign Key in the memberName table.
Table 1: memberName, memberAddress, driverName (foreign key), carRate($), totalFee($)
Table 2: driverName (primary key), yearsWorked
This ensures data integrity as the yearsWorked data would only need to be updated in the one cell now instead of multiple cells.

3NF - every field in a table must relate directly to the primary key
carRate($) is dependent on the size of the car. I'd add a foreign key field to table1 carSize which would become a primary key field in the third table.
Table 1: memberName, memberAddress, driverName (foreign key), carSize (foreign key)
Table 2: driverName (primary key), yearsWorked
Table 3: carSize, carRate($)

This leaves us with what I beleive should be a calculated field, totalFee($).
totalFee($): [yearsWorked]*[carRate($)]

I may have 2NF and 3NF in the wrong order.

Unfortunately, I didn't go over this in a lot of depth with my students, I expected that they would have the choice of which Normal Form they solved for, like the VCAA sample exam so we focused on 1NF more heavily than the other two normal forms.

Peter Langham
Narre Warren South P-12

On Wed, Nov 14, 2012 at 9:30 AM, Mark Scott <msc at luther.vic.edu.au<mailto:msc at luther.vic.edu.au>> wrote:

Mark

It will be Q9 (the Normalisation one) that will be the one most poorly answered.

I am looking forward to seeing your solution for that one.

:)

Mark Scott
Luther College

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From: itapps-bounces at edulists.com.au<mailto:itapps-bounces at edulists.com.au> [mailto:itapps-bounces at edulists.com.au<mailto:itapps-bounces at edulists.com.au>] On Behalf Of Mark KELLY
Sent: Wednesday, 14 November 2012 9:15 AM
To: Year 12 IT Applications Teachers' Mailing List
Subject: [Year 12 IT Apps] NINE mark question??

I wonder what the logic was behind changing the eight mark question into a nine mark question.

Was it something like, "Let's take the question that was most poorly answered last year and make it even more difficult." ?

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