[Informatics] An ERD challenge for you

[Mark]

Hi, file-comparers

Out of idle curiosity, I wondered whether the Digipubs' *Advice for
Teachers* pages
<http://www.digipubs.vic.edu.au/vcaa/vce-computing/vce-computing-introduction>
had changed since they were first uploaded .
I archived them on 16 December 2015 so I had a handy reference against
which to compare a fresh download of the files.

Results:

A minor point : the original
*vce-computing-units-3-and-4-software-dev-unit-3-learning.htm*
had been deleted. I suspect it had always been orphaned, since there is
*vce-computing-unit-3-software-dev-unit-3-learning2.htm*
which is named inconsistently ; all of the other related files start with
"vce-computing-units-*3-and-4*" but this one doesn't, so it sits awkwardly
out of place in the file list.

I did a byte-by-byte comparison between all of the archived files and the
freshly-downloaded versions (using a handy online file-comparison website
<https://www.diffchecker.com>) and found no differences in the body text,
which was reassuring.

Mark





On 25 August 2016 at 11:29, Mark <mark at vceit.com> wrote:

> The previous study design had ERDs, but their mandated style was an
> unnamed and incomplete mish-mash VCAA version of Chen with no cardinality
> indicators.
>
> I believe Crow's feet is the more common type of ERD used in real database
> development. Real database schema look very 'crowy'.
>
> It is good that VCAA is adopting Real World Models rather than half-baking
> their own.
>
> I am curious, however, why VCAA publishes a precise model for ERDs, but
> the style of UFD is left completely open.
>
> Mark
>
>
> On 25 August 2016 at 09:37, Stephen Trouse <Stephen.Trouse at flinders.vic.
> edu.au> wrote:
>
>> Let me display my utter ignorance here.  The first time I had ever seen
>> the terms “Chen” and “Crows-foot” notation was in the trial exam
>>
>>
>>
>> *From:* informatics-bounces at edulists.com.au [mailto:
>> informatics-bounces at edulists.com.au] *On Behalf Of *Mark
>> *Sent:* Tuesday, 23 August 2016 12:16 PM
>> *To:* Year 12 VCE Informatics Teachers' Mailing List <
>> informatics at edulists.com.au>
>> *Subject:* [Informatics] An ERD challenge for you
>>
>>
>>
>> Hi, entities.  Thanks to those who responded for my call yesterday for a
>> reality check.
>>
>>
>> The problem I had was that I got the ERD conventions document from the
>> VCAA site as soon as it was announced in April.
>>
>>
>>
>> This is what was in the section on cardinality:
>>
>>
>>
>> [image: cid:ii_is6slf261_156b5035534f7c31]
>> ​
>>
>> It's obviously wrong. Puzzled, I downloaded a new copy from the VCAA site
>> yesterday and found this:
>>
>>
>>
>> [image: cid:ii_is6smnlf2_156b50436b2b34ac]
>> ​
>>
>> But other people who downloaded the ERD document *on the same day I did*
>> got the 'proper' version. I can't imagine a corrupted download neatly
>> cropping parts of an image like that.
>>
>>
>>
>> The only explanation I could see is that VCAA uploaded the dodgy version
>> (which I got), noticed the fault and quickly amended and re-uploaded the
>> doc (which others got.)
>>
>>
>>
>> If this is the case, I would beg of VCAA to include version numbers in
>> their documents - and a revision history - so users can be sure they are
>> not using outdated documents. And I certainly hope VCAA announces document
>> updates in the bulletin.
>>
>>
>>
>> Thanks again
>>
>>
>>
>> P.S. The reason for the close inspection of the document was to update my
>> ERD powerpoint for the new study design.
>>
>> It is on my site at http://vceit.com/ppt2016/Design-Tools-ERD.pptx
>>
>>
>>
>>
>>
>> --
>>
>>
>>
>> Mark Kelly
>>
>>
>>
>> mark at vceit.com
>>
>> http://vceit.com
>>
>>
> --
>
> Mark Kelly
>
> mark at vceit.com
> http://vceit.com
>



-- 

Mark Kelly

mark at vceit.com
http://vceit.com
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