[Informatics] ERD policy

[Mark]

Hi Natalie

When I first saw "1:n" and "n:m" I also thought it must be a typo. I
assumed 'm' was short for 'many'.

Research revealed that for 'both m and n refer to 'many' in the sense of
"m" items on one side are related to  "n" items on the other side, and
"1:n" means 1 item on one side is related to n items on the other side.

People explain it at
http://stackoverflow.com/questions/3397349/meaning-of-nm-and-1n-in-database-design

Cheers
Mark

On 18 April 2016 at 11:34, Heath, Natalie <
Natalie.Heath at marcellin.vic.edu.au> wrote:

> Thanks Mark. I wish I’d had this when I was actually teaching it…. Last
> term….
>
>
>
> Quick question. On page 3 the sample has 1:N library member borrows book….
> Shouldn’t this be 1:M? Or am I missing something? 1:N isn’t in the list
> above it so I’m nicely confused.
>
>
>
> Natalie
>
>
>
> *Mrs Natalie Heath*
>
> ICT Learning Coordinator
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> *From:* informatics-bounces at edulists.com.au [mailto:
> informatics-bounces at edulists.com.au] *On Behalf Of *Mark
> *Sent:* Monday, 18 April 2016 11:12 AM
> *To:* Year 12 VCE Informatics Teachers' Mailing List
> *Subject:* [Informatics] ERD policy
>
>
>
> Hi folks. The long-awaited VCAA Entity Relationship Diagram policy
> <http://www.vcaa.vic.edu.au/Documents/vce/computing/Informatics_examination_ER_Conventions.docx>
> is out.
>
>
>
> And it includes cardinality with both Chen "1/M/N" and crowsfeet notations!
>
>
>
> Finally!
>
>
>
> --
>
>
>
> Mark Kelly
>
>
>
> mark at vceit.com
>
> http://vceit.com
>
> Natalie Heath
> Marcellin Staff
>
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-- 

Mark Kelly

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