[Year 12 IT Apps] Data Normalisation

Thu Apr 26 18:57:20 EST 2012

I did make an error that I noticed after I sent it, in the 3NF section there
is only meant to be ProdID, Book, Cost - not Item. The intention of adding a
CustID field was to add a Primary Key to the table, as it has to be Unique,
each CustID number relates to each individual customer - that was its
intention anyway. My 1NF was simply just to split up data such as Name and
Address into separate columns, which is suggested to do. Did I need to
include ProductID at all as this was something else that I also decided to
include to uniquely identify each book. I could probably just use the Books
Name as the Primary Key could I not, as each book is Unique? I understand
the concept of Normalising data but I'm unsure where I've actually gone
wrong here? I know in 3NF all fields must directly relate back to the
Primary Key - I wasn't sure however if "Date of Purchase" was actually
required in the table I've called "Orders"... 

The intention of this data from looking at it would be to have Customers
details stored in a table ("Customers").
A list of all the books for sale and their price ("Products"). 
And a table to fill in for orders ("Orders"). 

What step/s have I done wrong/missed out? 

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Today's Topics:

   1. Data Normalisation (POLLOCK, Benn(POL))
   2. Re: Data Normalisation (Robert Timmer-Arends)

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Message: 1
Date: Thu, 26 Apr 2012 14:56:22 +1000
From: "POLLOCK, Benn(POL)" <POL at wantirnacollege.vic.edu.au>
Subject: [Year 12 IT Apps] Data Normalisation
To: <itapps at edulists.com.au>
Message-ID:

<29963D9395C11C428DA4E6DA31456638032EA4C0 at want4.wantirnacollege.vic.edu.au>

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Covering Data Normlisation at the moment. First time I've attempted
this/taught this so I would appreciate any feedback you can give. I've
attached an excel document with some Data that I gave to the students to
practice with, and I've just had a go at it myself - could someone tell me
if It's correct? Going by everything I've read and other examples, it looks
right to me but I could be wrong! Appreciate any feedback. 

Benn Pollock

Information Technology Teacher

Wantirna College

Ph: 9801 9700

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Message: 2
Date: Thu, 26 Apr 2012 18:10:25 +1000
From: "Robert Timmer-Arends" <timmer at westnet.com.au>
Subject: Re: [Year 12 IT Apps] Data Normalisation
To: "Year 12 IT Applications Teachers' Mailing List"
	<itapps at edulists.com.au>
Message-ID: <1A7F11EB17E74DC9A6F84F53B37567CA at timmerarends>
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Hello Benn

I'm not sure about your 2NF and 3NF because I'm not sure what 'cost', 'item
cost' and 'item' are in relation to the original field 'item cost'.
However, as far as I can tell, except for one thing your first set of data
is already in 1NF because no record has a repeating group; eg two book
titles in the 'books purchased' field, or two equivalent fields such as
'books purchased 1' and 'books purchased 2'.

What is missing is a primary key that uniquely identifies each record. As
far as I can tell this would mean the primary key should be: 'name' and
'book purchased'

In your 1NF you have split fields which, for this example, is probably a
good idea, but not necessary to form 1NF; and you have added a 'cust id'
field presumably as a primary key, but as pointed out above this will not
uniquely identify a record, unless the intention is that 'cust id' is unique
for each book purchased by each customer. I suspect that this is not
intended so 'book' should also be italicised, indicating that it forms part
of the primary key.

Once set up like this, one recognises that it is not in 2NF because there
are fields that are dependent only on part of the primary key, thereby
leading to the split tables as you have done.

Regards
Robert T-A

----- Original Message -----
  From: POLLOCK, Benn(POL)
  To: itapps at edulists.com.au
  Sent: Thursday, April 26, 2012 2:56 PM
  Subject: [Year 12 IT Apps] Data Normalisation

  Covering Data Normlisation at the moment. First time I've attempted
this/taught this so I would appreciate any feedback you can give. I've
attached an excel document with some Data that I gave to the students  to
practice with, and I've just had a go at it myself - could someone tell me
if It's correct? Going by everything I've read and other examples, it looks
right to me but I could be wrong! Appreciate any feedback. 

  Benn Pollock

  Information Technology Teacher

  Wantirna College

  Ph: 9801 9700

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