[Year 12 IT Apps] itapps Digest, Vol 117, Issue 1
Sarup, Mahesh P
Sarup.Mahesh.P at edumail.vic.gov.au
Wed Nov 5 10:41:23 EST 2014
Hi Georgina
Homework
10 D IT: Flash Cards - Academic Vocab
10 D Physics - Worksheet on series and parallel circuit
11D Maths Method: Chapter 12 Review.
Thanks
Mahesh
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Today's Topics:
1. First Normal Form (Stephanie Polan)
2. New Digital Technologies curriculum: survey focusing on
teacher support (Christophersen, Paula P)
3. Re: First Normal Form (Mark)
4. Third Normal Form (Mark)
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Message: 1
Date: Wed, 5 Nov 2014 08:53:24 +1100
From: Stephanie Polan <pos at mckinnonsc.vic.edu.au>
Subject: [Year 12 IT Apps] First Normal Form
To: "Year 12 IT Applications Teachers' Mailing List"
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Good Morning everyone,
I know this is crazy... but my 12's are making me crazy, does anyone have any simple blunt help for Normal Form's ie 1NF 2NF. I've gone through my explanations and Mark Kelly's slide show and my patience and my students are still asking for clarification because of course they can learn and remember it for Friday!!!
Thanks in advance
Stephanie Polan
--
Miss Polan
McKinnon SC
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Message: 2
Date: Tue, 4 Nov 2014 22:02:59 +0000
From: "Christophersen, Paula P"
<christophersen.paula.p at edumail.vic.gov.au>
Subject: [Year 12 IT Apps] New Digital Technologies curriculum: survey
focusing on teacher support
To: "itapps at edulists.com.au" <itapps at edulists.com.au>,
"yr11it at edulists.com.au" <yr11it at edulists.com.au>, "Year 12 Software
Development Teachers' Mailing List" <sofdev at edulists.com.au>,
"cs4hs at edulists.com.au" <cs4hs at edulists.com.au>
Cc: "Paraskevopoulos, Helen \(DSD\)"
<Helen.Paraskevopoulos at dsdbi.vic.gov.au>, "Robinson, Glenys \(DSD\)"
<Glenys.Robinson at dsdbi.vic.gov.au>, "Steve Gale
\(SGALE at gordontafe.edu.au\)" <SGALE at gordontafe.edu.au>, "Rogan, Darryl
\(DSD\)" <Darryl.Rogan at dsdbi.vic.gov.au>
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<5D4D3BC6C28DDC418FFF0D843A798DF0684B3AD5 at EDUMBX03.education.vic.gov.au>
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Dear colleagues
It is planned that the new Digital Technologies curriculum will be fully implemented in Victorian government and Catholic schools in 2017. While the national review of the Australian Curriculum has slightly delayed the publishing of the Digital Technologies curriculum on the AusVELS website (now scheduled for early 2015), schools can begin to plan for their implementation of, or can introduce the curriculum from 2015, using the curriculum at: http://www.australiancurriculum.edu.au/technologies/digital-technologies/curriculum/f-10?layout=1 For many schools and teachers, this will require careful planning and the acquisition of new skills and knowledge, as students should be given the opportunity to demonstrate the standards up to level 10. This does not necessarily mean that you must timetable standalone offerings of Digital Technologies, but you need to consider how best to teach this curriculum in your school.
I have been working with a team of people, including Digital Learning and Teaching Victoria representation, involved in realising the Victorian ICT Workforce Development Plan, and part of this charter is to provide support for ICT/IT educators. As such, we would like to know what support you need to implement this new Digital Technologies curriculum. We need your input to make the best decisions and you can do this by completing the survey located at: http://fs2.formsite.com/diirdwebteam3/digitalcareers/index.html
The closing date for the survey is Friday 14 November.
Regards
Paula
Paula Christophersen
Curriculum Manager, Digital Technologies Victorian Curriculum and Assessment Authority
2 Lonsdale Street
MELBOURNE 3000
(03) 9032 1724
0407 043 110
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Message: 3
Date: Wed, 5 Nov 2014 09:39:29 +1100
From: Mark <mark at vceit.com>
Subject: Re: [Year 12 IT Apps] First Normal Form
To: "Year 12 IT Applications Teachers' Mailing List"
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Hi Stephanie. Now you know why I bailed out when I did :-)
1NF is easy:
- there must be no repeated columns (fields) e.g. Contact person 1, Contact person 2, Contact person 3.
- there may only be one datum in any field - i.e. no "16kg" "3 minutes 56 seconds", "Large Size $4, Small $2.50", "16 Fred St, Melbourne, 3000".
2NF problems ONLY arise if you're silly enough to use a multi-field key (e.g. using firstname & familyname to uniquely identify people in a table).
2NF problems never even arise if each table has its own dedicated key field (e.g. ID, account number).
But anyway, kids are expected to know 2NF.
2NF requires:
- 1NF has already been achieved.
- Any non-key field in a table is dependent on ALL of the fields used as the primary key.
As usual, this means as little as American football, so an example is needed.
There's a table with the following fields. 1NF has already been achieved.
StudentID
SubjectID
Mark
SubjectName
e.g. (Hope the formatting is not mangled - wish I could insert a table)
*STUDENTID SUBJECTID Mark SubjectName*
SMI0001 ENG A+ English
SMI0001 MA B Maths
FRE0002 ENG C English
The table's key is STUDENTID and SUBJECTID (together) to uniquely identify each record in the table.
The (non-key) MARK field is dependent on both STUDENTID and SUBJECTID - i.e. to find out what a mark refers to, you need to know both the student and subject.
However, the (non-key) SUBJECTNAME field is dependent only the SUBJECTID - i.e. to find out what a subject name refers to, you only need the SUBJECTID. You don't need the STUDENTID.
So the (non-key) SUBJECTNAME field is dependent on *part of* the key
(SUBJECTID) but not the *whole* key (STUDENTID+SUBJECTID).
So it fails 2NF.
To fix the problem, the table must be broken into two -
- MARKS_TABLE with STUDENTID+SUBJECTID as its key. It also contains the MARK non-key field.
- SUBJECTS_TABLE with SUBJECTID (primary key) and non-key SUBJECTNAME.
You then create a relationship between the MARKS table and the SUBJECTS table using their primary keys as the related fields.
Now, in the MARKS table, a Mark is dependent upon the entire key in its table (STUDENTID+SUBJECTID).
In the SUBJECTS table, a subject name is dependent on the entire key in its table (SUBJECTID).
Bingo. 2NF.
Hope that helps.
On 5 November 2014 08:53, Stephanie Polan <pos at mckinnonsc.vic.edu.au> wrote:
> Good Morning everyone,
>
> I know this is crazy... but my 12's are making me crazy, does anyone
> have any simple blunt help for Normal Form's ie 1NF 2NF. I've gone
> through my explanations and Mark Kelly's slide show and my patience
> and my students are still asking for clarification because of course
> they can learn and remember it for Friday!!!
>
> Thanks in advance
> Stephanie Polan
>
> --
> Miss Polan
> McKinnon SC
>
> _______________________________________________
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> http://www.vitta.org.au - VITTA Victorian Information Technology
> Teachers Association Inc <br> http://www.swinburne.edu.au/ict/schools
> - Swinburne University
>
--
Mark Kelly
mark AT vceit DOT com
http://vceit.com
*I love the sound of people's voices after they stop talking.*
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Message: 4
Date: Wed, 5 Nov 2014 10:20:36 +1100
From: Mark <mark at vceit.com>
Subject: [Year 12 IT Apps] Third Normal Form
To: "Year 12 IT Applications Teachers' Mailing List"
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Hello workers.
In case anyone was waiting for the other shoe to drop, let's cover 3NF.
To achieve 3NF:
- You must have already achieved 1NF and 2NF.
- No non-key field may be dependent on another non-key field.
Another way of saying it is that every non-key field in a table must give some information about the primary key rather than any other key in the table. Any field that does not contribute to the description of the primary key must be removed from the table.
For example... take a table. StudentID+SubjectID together are the primary key. (BTW - this use of multi-field keys is always to be avoided in the real world, but never mind for now.)
Honours is a Boolean field that is True if Mark is A or above, and False otherwise.
StudentID SubjectID Mark Honours
ABC0001 S01 A True
ABC0001 S02 A+ True
DEF0002 S01 B False
The Honours field is dependent on the Mark field (i.e. to find the meaning of the Honours field, you need to refer to the Mark field) - but the Mark field is not the table's primary key. i.e. The Honours field describes the mark, not the student+subject.
So, a non-key field (Honours) is dependent on another non-key field (Mark).
So it fails 3NF.
To fix it, do the same as we did before to achieve 2NF... break the offending field away into its own table with its own primary key (Mark) and non-key field (Honours) and relate the new table to the existing one using Mark as the link field.
This 3NF scenario looks VERY much like the 2NF before, doesn't it?
The only difference is that 2NF needed a non-key field to relate to the entire set of fields acting as the primary key.
In 3NF, it's actually simpler - a non-key field must not be dependent on another non-key field. In both cases, the fix is the same: table splitting. In my opinion, 3NF should be called 1.5NF because it seems to be more basic that 2NF, but we must all revere the word of Codd.
Always remember the normalisation oath:
The key (1NF), the whole key (2NF) and nothing but the key (3NF), so help me Codd <http://en.wikipedia.org/wiki/Edgar_F._Codd>.
(It's taken me 4 years, but I think I'm *finally* getting the hang of normalisation).
--
Mark Kelly
mark AT vceit DOT com
http://vceit.com
*I love the sound of people's voices after they stop talking.*
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