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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>A better question would be <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>“Why are they so vague?”<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>And then<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>“What is the purpose of the lack of precision in a subject that
is mostly about being precise?”<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>The answers to those questions would illuminate many of the areas
of confusion……. <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>So talk to people who were on the panel of the current study
design<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Andrew Shortell<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Braemar College<o:p></o:p></span></p>
</div>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<div>
<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> sofdev-bounces@edulists.com.au
[mailto:sofdev-bounces@edulists.com.au] <b>On Behalf Of </b>Russell Quinn<br>
<b>Sent:</b> Wednesday, 15 October 2008 3:10 PM<br>
<b>To:</b> sofdev@edulists.com.au<br>
<b>Subject:</b> [Year 12 SofDev] RE: Database question and confusion<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<div id=idOWAReplyText36118>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Another excellent reason for having a properly</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>defined
course. Our current VCAA statements</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>only
breed confusion and inefficiency. They wast</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>out
time and there students time, esp. when there</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>is
precious little time to spare. But no</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>one
ever seems to listen or respond.</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
</div>
<div id=idSignature40901>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif";
color:black'>Russell Quinn</span><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal> <o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><span style='font-size:10.0pt;font-family:"Arial","sans-serif"'>Mailto:
<a href="mailto:qn@boxhillhs.vic.edu.au" target="_blank">qn@boxhillhs.vic.edu.au</a></span><o:p></o:p></p>
</div>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
<div class=MsoNormal align=center style='text-align:center'>
<hr size=2 width="100%" align=center>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'><b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> sofdev-request@edulists.com.au<br>
<b>Sent:</b> Tue 14/10/2008 1:00 PM<br>
<b>To:</b> sofdev@edulists.com.au<br>
<b>Subject:</b> sofdev Digest, Vol 44, Issue 4</span><o:p></o:p></p>
</div>
<div><pre style='WORD-WRAP: break-word'>Send sofdev mailing list submissions to<o:p></o:p></pre><pre> sofdev@edulists.com.au<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>To subscribe or unsubscribe via the World Wide Web, visit<o:p></o:p></pre><pre> http://www.edulists.com.au/mailman/listinfo/sofdev<o:p></o:p></pre><pre>or, via email, send a message with subject or body 'help' to<o:p></o:p></pre><pre> sofdev-request@edulists.com.au<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>You can reach the person managing the list at<o:p></o:p></pre><pre> sofdev-owner@edulists.com.au<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>When replying, please edit your Subject line so it is more specific<o:p></o:p></pre><pre>than "Re: Contents of sofdev digest..."<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>Today's Topics:<o:p></o:p></pre><pre><o:p> </o:p></pre><pre> 1. RE: Database question (Quentin Lydall)<o:p></o:p></pre><pre> 2. Re: Database question (Mark Kelly)<o:p></o:p></pre><pre> 3. Re: Special thanks to Associate Professor Steven Bird<o:p></o:p></pre><pre> (Kevork Krozian)<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>----------------------------------------------------------------------<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Message: 1<o:p></o:p></pre><pre>Date: Tue, 14 Oct 2008 12:10:07 +1100<o:p></o:p></pre><pre>From: "Quentin Lydall" <qly@beaconhills.vic.edu.au><o:p></o:p></pre><pre>Subject: RE: [Year 12 SofDev] Database question<o:p></o:p></pre><pre>To: "Year 12 Software Development Teachers' Mailing List"<o:p></o:p></pre><pre> <sofdev@edulists.com.au><o:p></o:p></pre><pre>Message-ID:<o:p></o:p></pre><pre> <AFC3563D81D1044097735D5F6A3DBBE5014D7B6E@valley02.Beaconhills.beaconhills.vic.edu.au><o:p></o:p></pre><pre> <o:p></o:p></pre><pre>Content-Type: text/plain; charset="UTF-8"<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>I agree. Students should understand normalization, primary and foreign keys, lookup tables, data types and their properties, etc. There just is a fundamental logic error in the formulation of this answer, in a database context. Maybe it was done late at night..<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Quentin Lydall<o:p></o:p></pre><pre>Head of ICT<o:p></o:p></pre><pre>Beaconhills College Valley Campus<o:p></o:p></pre><pre>30-34 Toomuc Valley Road,<o:p></o:p></pre><pre>Pakenham<o:p></o:p></pre><pre>3810<o:p></o:p></pre><pre>Phone: 1300 002 225 Extn 3016<o:p></o:p></pre><pre> Please consider the environment before printing my email<span
style='font-family:Symbol'>P</span><o:p></o:p></pre><pre><o:p> </o:p></pre><pre>-----Original Message-----<o:p></o:p></pre><pre>From: sofdev-bounces@edulists.com.au [mailto:sofdev-bounces@edulists.com.au] On Behalf Of Steven Bird<o:p></o:p></pre><pre>Sent: Tuesday, 14 October 2008 11:58 AM<o:p></o:p></pre><pre>To: Year 12 Software Development Teachers' Mailing List<o:p></o:p></pre><pre>Subject: Re: [Year 12 SofDev] Database question<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>On Tue, Oct 14, 2008 at 11:13 AM, Adrian Janson<o:p></o:p></pre><pre><janson.adrian.a@edumail.vic.gov.au> wrote:<o:p></o:p></pre><pre>> Yes – quite correct. My students spotted this as well. The x5 is not<o:p></o:p></pre><pre>> required.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>There's some other problems though. A database with 20,000 customers<o:p></o:p></pre><pre>should have one or more indexes to support efficient retrieval, and<o:p></o:p></pre><pre>these take space. Nightly dumps take space as well. If the question<o:p></o:p></pre><pre>is getting at how much disk space we should budget for, these factors<o:p></o:p></pre><pre>are relevant.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>It would be bad database design to store postcode and suburb with each<o:p></o:p></pre><pre>customer record (cf [1]). Instead a customer record should contain a<o:p></o:p></pre><pre>foreign key to a table of postcodes, e.g. a subset of [2]. We're told<o:p></o:p></pre><pre>the company only has sales in a "local area", so perhaps we'd only<o:p></o:p></pre><pre>have to deal with a dozen postcodes. That table would be a constant<o:p></o:p></pre><pre>size overhead which is easy to compute, and the foreign key would be a<o:p></o:p></pre><pre>short integer (e.g. TINYINT).<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>The question treats a database as if it was a spreadsheet, and only<o:p></o:p></pre><pre>requires students to know the relative sizes of characters, bytes, and<o:p></o:p></pre><pre>bits.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>It would be good if students learnt about normalization and the<o:p></o:p></pre><pre>importance of avoiding duplication in a database. It would also be<o:p></o:p></pre><pre>nice if they learnt what Unicode is, and that 1 character != 1 byte.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>[1] http://en.wikipedia.org/wiki/Database_normalization<o:p></o:p></pre><pre>[2] http://www1.auspost.com.au/download/pc-full.zip<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>-Steven Bird<o:p></o:p></pre><pre>http://www.csse.unimelb.edu.au/~sb/<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>> A database for an online marketing company keeps records of all customers<o:p></o:p></pre><pre>> who have requested coupons and notifications of sales in their local area.<o:p></o:p></pre><pre>> They currently have a dedicated customer base of around 5000 customers, but<o:p></o:p></pre><pre>> wish to grow this to 20,000 customers within the next 5 years. How much<o:p></o:p></pre><pre>> storage capacity will be required to store 20,000 customer records for the<o:p></o:p></pre><pre>> entire 5 year period, given the following information:<o:p></o:p></pre><pre>> First Name – 50 characters<o:p></o:p></pre><pre>> Last Name – 50 characters<o:p></o:p></pre><pre>> Address – 100 characters<o:p></o:p></pre><pre>> Suburb – 50 characters<o:p></o:p></pre><pre>> Phone number – 10 characters each (2 phone numbers per customer)<o:p></o:p></pre><pre>> Email address – 50 characters<o:p></o:p></pre><pre>> Postcode – 4 characters<o:p></o:p></pre><pre>> Number of coupons received – 32-bit number<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> A. 34,200,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> B. 32,400,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> C. 35,600,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> D. 32,800,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> The solution gives D with the explanation<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 50+50+100+50+10+10+50+4+4 =<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 328<o:p></o:p></pre><pre>> 328 x 20000 x 5 = 32,800,000<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Why multiply by 5? Would the company recreate the entire records each<o:p></o:p></pre><pre>> year? I'd design it differently..<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> Appreciate your help.<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> Quentin Lydall<o:p></o:p></pre><pre>> Head of ICT<o:p></o:p></pre><pre>> Beaconhills College Valley Campus<o:p></o:p></pre><pre>> 30-34 Toomuc Valley Road,<o:p></o:p></pre><pre>> Pakenham<o:p></o:p></pre><pre>> 3810<o:p></o:p></pre><pre>> Phone: 1300 002 225 Extn 3016<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> P Please consider the environment before printing my email<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>#####################################################################################<o:p></o:p></pre><pre>This email is confidential and intended solely for the use of the individual to whom <o:p></o:p></pre><pre>it is addressed. Any views or opinions presented are solely those of the author and <o:p></o:p></pre><pre>do not necessarily represent those of Beaconhills College. If you are not the <o:p></o:p></pre><pre>intended recipient, be advised that you have received this email in error and that <o:p></o:p></pre><pre>any use, dissemination, forwarding, printing, or copying of this email is strictly <o:p></o:p></pre><pre>prohibited.<o:p></o:p></pre><pre>If you have received this email in error please notify Beaconhills College <o:p></o:p></pre><pre>by telephone on (+61 3) 1300 002 225.<o:p></o:p></pre><pre>#####################################################################################<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>------------------------------<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Message: 2<o:p></o:p></pre><pre>Date: Tue, 14 Oct 2008 12:51:48 +1100<o:p></o:p></pre><pre>From: Mark Kelly <kel@mckinnonsc.vic.edu.au><o:p></o:p></pre><pre>Subject: Re: [Year 12 SofDev] Database question<o:p></o:p></pre><pre>To: "Year 12 Software Development Teachers' Mailing List"<o:p></o:p></pre><pre> <sofdev@edulists.com.au><o:p></o:p></pre><pre>Message-ID: <48F3FB34.3010003@mckinnonsc.vic.edu.au><o:p></o:p></pre><pre>Content-Type: text/plain; charset=windows-1252; format=flowed<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>I see what you mean, but I think the question writer just used a <o:p></o:p></pre><pre>database as a vehicle for interrogating students' knowledge of number <o:p></o:p></pre><pre>types.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Since database structure is not part of the study design, a question <o:p></o:p></pre><pre>that required knowledge of indexes, normalisation, and relational links <o:p></o:p></pre><pre>etc could not, IMO, be justified.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>2 cents worth (and devaluing rapidly). Only a year without teaching SD <o:p></o:p></pre><pre>and my memory of it is getting rusty already!<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Cheers<o:p></o:p></pre><pre>Mark<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Steven Bird wrote:<o:p></o:p></pre><pre>> On Tue, Oct 14, 2008 at 11:13 AM, Adrian Janson<o:p></o:p></pre><pre>> <janson.adrian.a@edumail.vic.gov.au> wrote:<o:p></o:p></pre><pre>>> Yes quite correct. My students spotted this as well. The x5 is not<o:p></o:p></pre><pre>>> required.<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> There's some other problems though. A database with 20,000 customers<o:p></o:p></pre><pre>> should have one or more indexes to support efficient retrieval, and<o:p></o:p></pre><pre>> these take space. Nightly dumps take space as well. If the question<o:p></o:p></pre><pre>> is getting at how much disk space we should budget for, these factors<o:p></o:p></pre><pre>> are relevant.<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> It would be bad database design to store postcode and suburb with each<o:p></o:p></pre><pre>> customer record (cf [1]). Instead a customer record should contain a<o:p></o:p></pre><pre>> foreign key to a table of postcodes, e.g. a subset of [2]. We're told<o:p></o:p></pre><pre>> the company only has sales in a "local area", so perhaps we'd only<o:p></o:p></pre><pre>> have to deal with a dozen postcodes. That table would be a constant<o:p></o:p></pre><pre>> size overhead which is easy to compute, and the foreign key would be a<o:p></o:p></pre><pre>> short integer (e.g. TINYINT).<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> The question treats a database as if it was a spreadsheet, and only<o:p></o:p></pre><pre>> requires students to know the relative sizes of characters, bytes, and<o:p></o:p></pre><pre>> bits.<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> It would be good if students learnt about normalization and the<o:p></o:p></pre><pre>> importance of avoiding duplication in a database. It would also be<o:p></o:p></pre><pre>> nice if they learnt what Unicode is, and that 1 character != 1 byte.<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> [1] http://en.wikipedia.org/wiki/Database_normalization<o:p></o:p></pre><pre>> [2] http://www1.auspost.com.au/download/pc-full.zip<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> -Steven Bird<o:p></o:p></pre><pre>> http://www.csse.unimelb.edu.au/~sb/<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>>> A database for an online marketing company keeps records of all customers<o:p></o:p></pre><pre>>> who have requested coupons and notifications of sales in their local area.<o:p></o:p></pre><pre>>> They currently have a dedicated customer base of around 5000 customers, but<o:p></o:p></pre><pre>>> wish to grow this to 20,000 customers within the next 5 years. How much<o:p></o:p></pre><pre>>> storage capacity will be required to store 20,000 customer records for the<o:p></o:p></pre><pre>>> entire 5 year period, given the following information:<o:p></o:p></pre><pre>>> First Name 50 characters<o:p></o:p></pre><pre>>> Last Name 50 characters<o:p></o:p></pre><pre>>> Address 100 characters<o:p></o:p></pre><pre>>> Suburb 50 characters<o:p></o:p></pre><pre>>> Phone number 10 characters each (2 phone numbers per customer)<o:p></o:p></pre><pre>>> Email address 50 characters<o:p></o:p></pre><pre>>> Postcode 4 characters<o:p></o:p></pre><pre>>> Number of coupons received 32-bit number<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>> A. 34,200,000 bytes<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> B. 32,400,000 bytes<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> C. 35,600,000 bytes<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> D. 32,800,000 bytes<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>> The solution gives D with the explanation<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> 50+50+100+50+10+10+50+4+4 =<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> 328<o:p></o:p></pre><pre>>> 328 x 20000 x 5 = 32,800,000<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Why multiply by 5? Would the company recreate the entire records each<o:p></o:p></pre><pre>>> year? I'd design it differently..<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Appreciate your help.<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Quentin Lydall<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Head of ICT<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Beaconhills College Valley Campus<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> 30-34 Toomuc Valley Road,<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Pakenham<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> 3810<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Phone: 1300 002 225 Extn 3016<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> P Please consider the environment before printing my email<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>><o:p> </o:p></pre><pre>>> ________________________________<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> This email is confidential and intended solely for the use of the<o:p></o:p></pre><pre>>> individual to whom it is addressed. Any views or opinions presented are<o:p></o:p></pre><pre>>> solely those of the author and do not necessarily represent those of<o:p></o:p></pre><pre>>> Beaconhills College. If you are not the intended recipient, be advised that<o:p></o:p></pre><pre>>> you have received this email in error and that any use, dissemination,<o:p></o:p></pre><pre>>> forwarding, printing, or copying of this email is strictly prohibited. If<o:p></o:p></pre><pre>>> you have received this email in error please notify Beaconhills College by<o:p></o:p></pre><pre>>> telephone on (+61 3) 1300 002 225.<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> ________________________________<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> _______________________________________________<o:p></o:p></pre><pre>>> http://www.edulists.com.au IT Software Development Mailing List kindly<o:p></o:p></pre><pre>>> supported by<o:p></o:p></pre><pre>>> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html -<o:p></o:p></pre><pre>>> Victorian Curriculum and Assessment Authority and<o:p></o:p></pre><pre>>> http://www.vitta.org.au - VITTA Victorian Information Technology Teachers<o:p></o:p></pre><pre>>> Association Inc<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> Important - This email and any attachments may be confidential. If received<o:p></o:p></pre><pre>>> in error, please contact us and delete all copies. Before opening or using<o:p></o:p></pre><pre>>> attachments check them for viruses and defects. Regardless of any loss,<o:p></o:p></pre><pre>>> damage or consequence, whether caused by the negligence of the sender or<o:p></o:p></pre><pre>>> not, resulting directly or indirectly from the use of any attached files our<o:p></o:p></pre><pre>>> liability is limited to resupplying any affected attachments. Any<o:p></o:p></pre><pre>>> representations or opinions expressed are those of the individual sender,<o:p></o:p></pre><pre>>> and not necessarily those of the Department of Education and Early Childhood<o:p></o:p></pre><pre>>> Development.<o:p></o:p></pre><pre>>><o:p> </o:p></pre><pre>>> _______________________________________________<o:p></o:p></pre><pre>>> http://www.edulists.com.au IT Software Development Mailing List kindly<o:p></o:p></pre><pre>>> supported by<o:p></o:p></pre><pre>>> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html -<o:p></o:p></pre><pre>>> Victorian Curriculum and Assessment Authority and<o:p></o:p></pre><pre>>> http://www.vitta.org.au - VITTA Victorian Information Technology Teachers<o:p></o:p></pre><pre>>> Association Inc<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> _______________________________________________<o:p></o:p></pre><pre>> http://www.edulists.com.au<o:p></o:p></pre><pre>> IT Software Development Mailing List kindly supported by<o:p></o:p></pre><pre>> http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment Authority and<o:p></o:p></pre><pre>> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html - VITTA Victorian Information Technology Teachers Association Inc<o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> <o:p></o:p></pre><pre>> <o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>-- <o:p></o:p></pre><pre>Mark Kelly<o:p></o:p></pre><pre>Manager - Information Systems<o:p></o:p></pre><pre>McKinnon Secondary College<o:p></o:p></pre><pre>McKinnon Rd McKinnon 3204, Victoria, Australia<o:p></o:p></pre><pre>Direct line / Voicemail: 8520 9085<o:p></o:p></pre><pre>School Phone +613 8520 9000<o:p></o:p></pre><pre>School Fax +613 95789253<o:p></o:p></pre><pre>kel AT mckinnonsc.vic.edu.au<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Webmaster - http://www.mckinnonsc.vic.edu.au<o:p></o:p></pre><pre>IT Lecture notes: http://vceit.com<o:p></o:p></pre><pre>Moderator: IT Applications Mailing List<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>A conclusion is the place where you got sick of thinking.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>------------------------------<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Message: 3<o:p></o:p></pre><pre>Date: Tue, 14 Oct 2008 11:58:39 +1100<o:p></o:p></pre><pre>From: "Kevork Krozian" <Kroset@novell1.fhc.vic.edu.au><o:p></o:p></pre><pre>Subject: Re: [Year 12 SofDev] Special thanks to Associate Professor<o:p></o:p></pre><pre> Steven Bird<o:p></o:p></pre><pre>To: "Year 12 Software Development Teachers' Mailing List"<o:p></o:p></pre><pre> <sofdev@edulists.com.au><o:p></o:p></pre><pre>Message-ID: <48F497EE.EE3E.0095.0@novell1.fhc.vic.edu.au><o:p></o:p></pre><pre>Content-Type: text/plain; charset=ISO-8859-15<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Hi Steven,<o:p></o:p></pre><pre><o:p> </o:p></pre><pre> I think we are very fortunate and privileged to have your time and<o:p></o:p></pre><pre>expertise on these lists. <o:p></o:p></pre><pre><o:p> </o:p></pre><pre>I am sure you have other pressing demands on your time not least of<o:p></o:p></pre><pre>which in your lecturing and related duties in the Uni of Melbourne<o:p></o:p></pre><pre>Computer Science faculty and other projects, research and activities you<o:p></o:p></pre><pre>are working on as recorded on http://www.csse.unimelb.edu.au/~sb/ .<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>Your explanations and insights into implications of certain questions<o:p></o:p></pre><pre>on both the final and practice exams in Software Development can only<o:p></o:p></pre><pre>help us all to become better teachers if for no other reason than the<o:p></o:p></pre><pre>seed it plants to think about problems from another perspective and<o:p></o:p></pre><pre>hopefully continue the discussion and seek further clarification.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre> So on behalf of the list membership, please keep your comments coming<o:p></o:p></pre><pre>and thanks for your time.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>Best Wishes<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>Kevork Krozian<o:p></o:p></pre><pre>IT Manager , Forest Hill College<o:p></o:p></pre><pre>k.krozian@fhc.vic.edu.au<o:p></o:p></pre><pre>http://www.fhc.vic.edu.au<o:p></o:p></pre><pre>Mobile: 0419 356 034<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>>>> "Steven Bird" <sb@csse.unimelb.edu.au> 14/10/2008 11:57 am >>><o:p></o:p></pre><pre>On Tue, Oct 14, 2008 at 11:13 AM, Adrian Janson<o:p></o:p></pre><pre><janson.adrian.a@edumail.vic.gov.au> wrote:<o:p></o:p></pre><pre>> Yes * quite correct. My students spotted this as well. The x5 is<o:p></o:p></pre><pre>not<o:p></o:p></pre><pre>> required.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>There's some other problems though. A database with 20,000 customers<o:p></o:p></pre><pre>should have one or more indexes to support efficient retrieval, and<o:p></o:p></pre><pre>these take space. Nightly dumps take space as well. If the question<o:p></o:p></pre><pre>is getting at how much disk space we should budget for, these factors<o:p></o:p></pre><pre>are relevant.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>It would be bad database design to store postcode and suburb with each<o:p></o:p></pre><pre>customer record (cf [1]). Instead a customer record should contain a<o:p></o:p></pre><pre>foreign key to a table of postcodes, e.g. a subset of [2]. We're told<o:p></o:p></pre><pre>the company only has sales in a "local area", so perhaps we'd only<o:p></o:p></pre><pre>have to deal with a dozen postcodes. That table would be a constant<o:p></o:p></pre><pre>size overhead which is easy to compute, and the foreign key would be a<o:p></o:p></pre><pre>short integer (e.g. TINYINT).<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>The question treats a database as if it was a spreadsheet, and only<o:p></o:p></pre><pre>requires students to know the relative sizes of characters, bytes, and<o:p></o:p></pre><pre>bits.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>It would be good if students learnt about normalization and the<o:p></o:p></pre><pre>importance of avoiding duplication in a database. It would also be<o:p></o:p></pre><pre>nice if they learnt what Unicode is, and that 1 character != 1 byte.<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>[1] http://en.wikipedia.org/wiki/Database_normalization <o:p></o:p></pre><pre>[2] http://www1.auspost.com.au/download/pc-full.zip <o:p></o:p></pre><pre><o:p> </o:p></pre><pre>-Steven Bird<o:p></o:p></pre><pre>http://www.csse.unimelb.edu.au/~sb/ <o:p></o:p></pre><pre><o:p> </o:p></pre><pre>> A database for an online marketing company keeps records of all<o:p></o:p></pre><pre>customers<o:p></o:p></pre><pre>> who have requested coupons and notifications of sales in their local<o:p></o:p></pre><pre>area.<o:p></o:p></pre><pre>> They currently have a dedicated customer base of around 5000<o:p></o:p></pre><pre>customers, but<o:p></o:p></pre><pre>> wish to grow this to 20,000 customers within the next 5 years. How<o:p></o:p></pre><pre>much<o:p></o:p></pre><pre>> storage capacity will be required to store 20,000 customer records<o:p></o:p></pre><pre>for the<o:p></o:p></pre><pre>> entire 5 year period, given the following information:<o:p></o:p></pre><pre>> First Name * 50 characters<o:p></o:p></pre><pre>> Last Name * 50 characters<o:p></o:p></pre><pre>> Address * 100 characters<o:p></o:p></pre><pre>> Suburb * 50 characters<o:p></o:p></pre><pre>> Phone number * 10 characters each (2 phone numbers per customer)<o:p></o:p></pre><pre>> Email address * 50 characters<o:p></o:p></pre><pre>> Postcode * 4 characters<o:p></o:p></pre><pre>> Number of coupons received * 32-bit number<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> A. 34,200,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> B. 32,400,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> C. 35,600,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> D. 32,800,000 bytes<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> The solution gives D with the explanation<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 50+50+100+50+10+10+50+4+4 =<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 328<o:p></o:p></pre><pre>> 328 x 20000 x 5 = 32,800,000<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Why multiply by 5? Would the company recreate the entire records<o:p></o:p></pre><pre>each<o:p></o:p></pre><pre>> year? I'd design it differently..<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> Appreciate your help.<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> Quentin Lydall<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Head of ICT<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Beaconhills College Valley Campus<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 30-34 Toomuc Valley Road,<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Pakenham<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> 3810<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Phone: 1300 002 225 Extn 3016<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> P Please consider the environment before printing my email<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>><o:p> </o:p></pre><pre>> ________________________________<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> This email is confidential and intended solely for the use of the<o:p></o:p></pre><pre>> individual to whom it is addressed. Any views or opinions presented<o:p></o:p></pre><pre>are<o:p></o:p></pre><pre>> solely those of the author and do not necessarily represent those of<o:p></o:p></pre><pre>> Beaconhills College. If you are not the intended recipient, be<o:p></o:p></pre><pre>advised that<o:p></o:p></pre><pre>> you have received this email in error and that any use,<o:p></o:p></pre><pre>dissemination,<o:p></o:p></pre><pre>> forwarding, printing, or copying of this email is strictly<o:p></o:p></pre><pre>prohibited. If<o:p></o:p></pre><pre>> you have received this email in error please notify Beaconhills<o:p></o:p></pre><pre>College by<o:p></o:p></pre><pre>> telephone on (+61 3) 1300 002 225.<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> ________________________________<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> _______________________________________________<o:p></o:p></pre><pre>> http://www.edulists.com.au IT Software Development Mailing List<o:p></o:p></pre><pre>kindly<o:p></o:p></pre><pre>> supported by<o:p></o:p></pre><pre>> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html -<o:p></o:p></pre><pre>> Victorian Curriculum and Assessment Authority and<o:p></o:p></pre><pre>> http://www.vitta.org.au - VITTA Victorian Information Technology<o:p></o:p></pre><pre>Teachers<o:p></o:p></pre><pre>> Association Inc<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> Important - This email and any attachments may be confidential. If<o:p></o:p></pre><pre>received<o:p></o:p></pre><pre>> in error, please contact us and delete all copies. Before opening or<o:p></o:p></pre><pre>using<o:p></o:p></pre><pre>> attachments check them for viruses and defects. Regardless of any<o:p></o:p></pre><pre>loss,<o:p></o:p></pre><pre>> damage or consequence, whether caused by the negligence of the sender<o:p></o:p></pre><pre>or<o:p></o:p></pre><pre>> not, resulting directly or indirectly from the use of any attached<o:p></o:p></pre><pre>files our<o:p></o:p></pre><pre>> liability is limited to resupplying any affected attachments. Any<o:p></o:p></pre><pre>> representations or opinions expressed are those of the individual<o:p></o:p></pre><pre>sender,<o:p></o:p></pre><pre>> and not necessarily those of the Department of Education and Early<o:p></o:p></pre><pre>Childhood<o:p></o:p></pre><pre>> Development.<o:p></o:p></pre><pre>><o:p> </o:p></pre><pre>> _______________________________________________<o:p></o:p></pre><pre>> http://www.edulists.com.au IT Software Development Mailing List<o:p></o:p></pre><pre>kindly<o:p></o:p></pre><pre>> supported by<o:p></o:p></pre><pre>> http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html -<o:p></o:p></pre><pre>> Victorian Curriculum and Assessment Authority and<o:p></o:p></pre><pre>> http://www.vitta.org.au - VITTA Victorian Information Technology<o:p></o:p></pre><pre>Teachers<o:p></o:p></pre><pre>> Association Inc<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>http://www.edulists.com.au <o:p></o:p></pre><pre>IT Software Development Mailing List kindly supported by<o:p></o:p></pre><pre>http://www.vcaa.vic.edu.au - Victorian Curriculum and Assessment<o:p></o:p></pre><pre>Authority and<o:p></o:p></pre><pre>http://www.vitta.org.au/vce/studies/infotech/softwaredevel3-4.html -<o:p></o:p></pre><pre>VITTA Victorian Information Technology Teachers Association Inc<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>------------------------------<o:p></o:p></pre><pre><o:p> </o:p></pre><pre>_______________________________________________<o:p></o:p></pre><pre>sofdev mailing list<o:p></o:p></pre><pre>sofdev@edulists.com.au<o:p></o:p></pre><pre>http://www.edulists.com.au/mailman/listinfo/sofdev<o:p></o:p></pre><pre><o:p> </o:p></pre><pre><o:p> </o:p></pre><pre>End of sofdev Digest, Vol 44, Issue 4<o:p></o:p></pre><pre>*************************************<o:p></o:p></pre></div>
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