[Informatics] An ERD challenge for you

[Heath, Natalie]

Thanks for doing that Mark – I’ve been comparing on an ad-hoc basis out of fear, convinced that I’ll miss something important.

Mrs Natalie Heath
ICT Learning Coordinator

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Marcellin College
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From: informatics-bounces at edulists.com.au [mailto:informatics-bounces at edulists.com.au] On Behalf Of Mark
Sent: Thursday, 25 August 2016 12:57 PM
To: Year 12 VCE Informatics Teachers' Mailing List
Subject: Re: [Informatics] An ERD challenge for you

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<mailto: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<mailto: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> [mailto: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<mailto: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:

[cid:ii_is6slf261_156b5035534f7c31]
​
It's obviously wrong. Puzzled, I downloaded a new copy from the VCAA site yesterday and found this:

[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<mailto:mark at vceit.com>
http://vceit.com


--

Mark Kelly

mark at vceit.com<mailto:mark at vceit.com>
http://vceit.com



--

Mark Kelly

mark at vceit.com<mailto:mark at vceit.com>
http://vceit.com

Natalie Heath
Marcellin Staff

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