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<DIV><FONT size=2 face=Arial>Hello all</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>just be careful with this site though. Its
definition of 1NF is not quite right and its 1NF example is wrong because of
it.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>In the following I am only referring to what
appears under the heading 'First Normal Form 1NF'</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>'A row of data cannot contain a repeating group' -
correct - note it's the row, not the column.</FONT></DIV>
<DIV><FONT size=2 face=Arial>'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'.</FONT></DIV>
<DIV><FONT size=2 face=Arial>'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.</FONT></DIV>
<DIV><FONT size=2 face=Arial>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</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>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.</FONT></DIV>
<DIV><FONT size=2 face=Arial>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.</FONT></DIV>
<DIV><FONT size=2 face=Arial>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.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Regards</FONT></DIV>
<DIV><FONT size=2 face=Arial>Robert T-A</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV>----- Original Message ----- </DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=htzelepis@msj.vic.edu.au href="mailto:htzelepis@msj.vic.edu.au">Litsa
Tzelepis</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=itapps@edulists.com.au
href="mailto:itapps@edulists.com.au">Year 12 IT Applications Teachers' Mailing
List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, April 29, 2014 2:59
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Year 12 IT Apps]
Normalisation Activity</DIV>
<DIV><BR></DIV>
<DIV dir=ltr>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif" class=gmail_default>hi
Sylvia - </DIV>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif"
class=gmail_default><BR></DIV>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif" class=gmail_default>would
this help a little?</DIV>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif"
class=gmail_default><BR></DIV>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif" class=gmail_default>litsa
:-)</DIV>
<DIV style="FONT-FAMILY: arial,helvetica,sans-serif"
class=gmail_default><BR></DIV>
<DIV class=gmail_default><FONT face="arial, helvetica, sans-serif"><A
href="http://www.studytonight.com/dbms/database-normalization.php">http://www.studytonight.com/dbms/database-normalization.php</A></FONT><BR></DIV>
<DIV class=gmail_default><FONT
face="arial, helvetica, sans-serif"><BR></FONT></DIV></DIV>
<DIV class=gmail_extra><BR><BR>
<DIV class=gmail_quote>On Tue, Apr 29, 2014 at 10:30 AM, Sylvia Pastore <SPAN
dir=ltr><<A href="mailto:smp191172@gmail.com"
target=_blank>smp191172@gmail.com</A>></SPAN> wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>
<DIV dir=ltr>Hi all
<DIV>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.</DIV>
<DIV><BR></DIV>
<DIV>Thanks in anticipation.</DIV><SPAN class=HOEnZb><FONT color=#888888>
<DIV>sylvia</DIV></FONT></SPAN></DIV><BR>_______________________________________________<BR><A
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<DIV><BR></DIV>-- <BR>
<DIV dir=ltr>
<DIV><FONT size=1>Litsa Tzelepis<BR>Mount St. Joseph Girls' College<BR>133
Maidstone Street, Altona, VIC. 3018<BR></FONT><A
href="mailto:htzelepis@msj.vic.edu.au" target=_blank><FONT
size=1>htzelepis@msj.vic.edu.au</FONT></A><BR><FONT size=1>P:8398 2000 |
F:9398 3498</FONT></DIV>
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