[Year 12 IT Apps] Normalisation Activity

[Litsa Tzelepis]

Thank you Robert. I completely didn't notice that. Thank you for clarifying
and sorry if anyone has been confused by it.

Ta, litsa :-)

On Thursday, May 1, 2014, Robert Timmer-Arends <timmer at westnet.com.au>
wrote:

>  Hello all
>
> just be careful with this site though. Its definition of 1NF is not quite
> right and its 1NF example is wrong because of it.
>
> In the following I am only referring to what appears under the heading
> 'First Normal Form 1NF'
>
> 'A row of data cannot contain a repeating group' - correct - note it's the
> row, not the column.
> 'Each column must have a unique value' - not correct. Think about it. In
> their example, this means you cannot have more than one student named
> 'Adam' or more than one appearance of the subject 'Maths'.
> 'Each row of data must have a unique identifier i.e primary key' - not
> quite. A primary key is the smallest number of columns that uniquely
> identify a row.
> In fact, for their example, the inital Student table, which they say is
> not 1NF IS in 1NF, with a primary key = S_ID + Subject
>
> The difficulty of course is that it uniquely identifies a student in a
> subject. Presumably the intention is for S_ID to be a primary key on its
> own, uniquely identifying a student.
> In that case, the reason the table must be split has nothing to do with
> 1NF. The reason is that it is NOT in 2NF (assuming we want S_ID as the
> unique identifier). 2NF says that no column that is not part of a primary
> key can be dependent on only a part of the primary key. Clearly S_Name is
> dependent only on S_ID, not on S_ID + Subject.
> So the split occurs as given, but leading to 2NF not 1NF (Yes, as they
> say, each of the split tables are in 1NF, but the two tables together are a
> 2NF representation of the initial Student table.
>
> Regards
> Robert T-A
>
> ----- Original Message -----
>
> *From:* Litsa Tzelepis<javascript:_e(%7B%7D,'cvml','htzelepis at msj.vic.edu.au');>
> *To:* Year 12 IT Applications Teachers' Mailing List<javascript:_e(%7B%7D,'cvml','itapps at edulists.com.au');>
> *Sent:* Tuesday, April 29, 2014 2:59 PM
> *Subject:* Re: [Year 12 IT Apps] Normalisation Activity
>
>  hi Sylvia -
>
> would this help a little?
>
> litsa :-)
>
> http://www.studytonight.com/dbms/database-normalization.php
>
>
>
> On Tue, Apr 29, 2014 at 10:30 AM, Sylvia Pastore <smp191172 at gmail.com<javascript:_e(%7B%7D,'cvml','smp191172 at gmail.com');>
> > wrote:
>
>> Hi all
>> Would anyone have an access normalisation activity for my kids to try.
>> Some of them are finding it a bit hard to grasp and thought someone may
>> have created one to save me some time.
>>
>> Thanks in anticipation.
>> sylvia
>>
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>
> --
>  Litsa Tzelepis
> Mount St. Joseph Girls' College
> 133 Maidstone Street, Altona, VIC. 3018
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