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<DIV><FONT size=2 face=Arial>I found this site to help as it hs many
examples:</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial><A
href="http://www.teach-ict.com/as_as_computing/ocr/H447/F453/3_3_9/normalisation/miniweb/index.htm">http://www.teach-ict.com/as_as_computing/ocr/H447/F453/3_3_9/normalisation/miniweb/index.htm</A></FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Follow the links on the left frame.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>However, as much as this confuses me, it looks like
the more you break down a table, to eliminate as much duplication as possible,
it goes up an NF level.</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Good luck, Litsa</FONT></DIV>
<DIV> </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">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=josephpapaleo@gmail.com href="mailto:josephpapaleo@gmail.com">Joseph
Papaleo</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> Monday, October 17, 2011 1:35
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Year 12 IT Apps] Normal
forms</DIV>
<DIV><BR></DIV>Mark,<BR>In a nutshell, I've taught it as :<BR><BR>1NF - tidy
the table(s) up horizontally<BR>ie Fields contain only a single value eg Name:
Mr Barney Rubble changes to <BR>Title: Mr<BR>Fname: Barney <BR>Sname:
Rubble<BR clear=all><BR>Remove repeating Groups (as per Mark's
comments)<BR><BR><BR>2NF - Tidy the table(s) up Vertically<BR>Eliminate
duplication in records down the table by using a Primary Key that each record
refers to.<BR>Continue to do this as often as required until duplication is
removed from all tables- students should see the need for a new table if there
is duplication with their own unique Primary Key.<BR><BR><BR>3NF - Make all
fields in a table Mutually Exclusive<BR>ie, no field can rely on
another. eg table may contain "Quantity" and "Price", but it cannot
contain "Total Cost" as Total cost = Quantity x Price.<BR><BR>I'm concerned
that my students understand this, but they found it difficult to do. Also
concerned that I may have used an old or inferior
resource.<BR><BR><BR><BR><BR>Joseph Papaleo<BR>Ivanhoe Grammar
School,<BR>Plenty Campus<BR><BR><BR><BR><BR>
<DIV class=gmail_quote>On Mon, Oct 17, 2011 at 1:04 PM, Mark KELLY <SPAN
dir=ltr><<A
href="mailto:kel@mckinnonsc.vic.edu.au">kel@mckinnonsc.vic.edu.au</A>></SPAN>
wrote:<BR>
<BLOCKQUOTE
style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex"
class=gmail_quote>Groan. I just spent another 30 minutes trying to
explain the differences between 2NF and 3NF to my dears. <BR>As usual,
by the time I finished, I think they knew less than when I
started.<BR><BR>1NF is pretty clear cut...<BR> - no duplicate rows
(i.e. identical records)<BR> - no multiple columns that contain the
same *type* of data (e.g. child1, child2, child3)<BR> - only one piece
of data per field (e.g. don't store 2 phone numbers for a person in the
'phone' field; put street address/suburb/postcode in separate fields; in
Filemaker, don't use repeating fields) <BR><BR>But 2NF is really only
a problem if you use *multiple* fields as a key (e.g. using firstname +
lastname + phone as a unique key) instead of using a unique and arbitrary
key field, like an ID number. <BR>I realise now that my kids have
trouble absorbing 2NF because at no time in their database education have I
ever *mentioned* the possibility of using multiple fields as the key. So
explaining 2NF to them was a bit like warning them not to walk using their
ears - the concept had never even dawned on them before. To them, having a
non-key field that did not give information about *all* of the key fields
was a strange and scary possibility.<BR><BR>3NF is, I think, relatively
straight forward. Each non-key field must give information about the key and
not to another non-key field. Violation of 3NF is usually pretty
obvious because it looks "strange".<BR><BR>After 2 slideshows, I'm still
trying to work out a way to make it sound really clear... next time,
maybe. If anyone has hit on a sure-fire summary of differentiating normal
forms, I'd love to hear of it.<BR><BR>Regards<BR><FONT color=#888888><BR>--
<BR>Mark Kelly<BR>Manager of ICT, Reporting, IT Learning Area<BR>McKinnon
Secondary College<BR>McKinnon Rd McKinnon 3204, Victoria,
Australia<BR>Direct line / Voicemail: <A href="tel:%2B613%208520%209085"
target=_blank value="+61385209085">+613 8520 9085</A>, Fax <A
href="tel:%2B613%209578%209253" target=_blank value="+61395789253">+613 9578
9253</A><BR><A href="mailto:kel@mckinnonsc.vic.edu.au"
target=_blank>kel@mckinnonsc.vic.edu.au</A><BR>VCE IT Lecture Notes: <A
href="http://vceit.com" target=_blank>http://vceit.com</A><BR>Moderator: <A
href="http://www.edulists.com.au/" target=_blank>IT Applications
Edulist</A><BR><BR><FONT size=+0>Want a good time? Call 0112358. Ask for Mr
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