[Informatics] An ERD challenge for you

[Mark]

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@
> 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 not using outdated documents.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
>
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-- 

Mark Kelly

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