[Year 12 IT Apps] ITA new design. Sorry - another one.

[Timmer-Arends]

Hello again Mark

what you say is true. I was talking about the process of 'normalisation' (see Kevork's tute), not referential integrity. If I understand your original email, the KK refers to 'integrity of data' not 'referential integrity'. 

I agree that normalisation cannot eliminate the possibilty of data losing its integrity (what's the opposite of integrity?), but it goes a long way to prevent silly things that could occur in a non-normalised db; eg imagine a db table containing teachers and their classes. Let's say there is a teacher code, first name, second name and class name field. I currently teach Maths and InfoTech so entries for me could be:
TIM, Robert, Timmer-Arends, Maths
TIM, Fred, Timmer-Arends, InfoTech

One person becomes two. Normalisation prevent this kind of thing by insisting that two tables be created, one for names, the other for classes, with a relationship between the two

(sorry if I'm stating the obvious)

Regards
Robert T-A






----- Original Message ----- 
  From: Mark KELLY 
  To: Year 12 IT Applications Teachers' Mailing List 
  Sent: Saturday, March 27, 2010 12:38 AM
  Subject: Re: [Year 12 IT Apps] ITA new design. Sorry - another one.


  Hi Robert.  MS Access has the 'enforce referential integrity' tickbox (or so I am led to believe) so RI is somewhat related to software implementation.

  And it can't be solely a database design issue.  

  Setting up 2 related tables - even with a perfect design - will not prevent accidental entry of a value which fails to find a match in a foreign key field.  

  RI, however, does detect data entries for which there is no foreign key field match and prevents/challenges their entry.

  2.2 cents' worth.


  On Fri, Mar 26, 2010 at 4:07 PM, Timmer-Arends <timmer at melbpc.org.au> wrote:

    Hello Mark

    'normalisation' refers to a process of database table design that eliminates 'flaws' in a design that could lead to data integrity problems. It is a software independent process.

    Regards
    Robert T-A
      ----- Original Message ----- 
      From: Mark KELLY 
      To: Year 12 IT Applications Teachers' Mailing List 
      Sent: Friday, March 26, 2010 3:02 PM
      Subject: [Year 12 IT Apps] ITA new design. Sorry - another one.


      Apologies for all the posts, but the new design is an interesting beast.

      ITA U3O2 Key Knowledge 11 - "ways in which normalisation can ensure the integrity of data in an RDBMS"

      Assuming they mean "referential integrity", this will be an interesting dotpoint if you're using Filemaker which does not use the concept of referential integrity*


      *Except as an awkward kludge by using a validation rule ("exists in limited list") and defining the list to include values in a foreign key field.

      -- 
      Mark Kelly
      Manager - Information Systems
      McKinnon Secondary College
      McKinnon Rd McKinnon 3204, Victoria, Australia
      Direct line / Voicemail: 8520 9085
      School Phone +613 8520 9000
      School Fax +613 9578 9253
      kel at mckinnonsc.vic.edu.au

      Webmaster - http://www.mckinnonsc.vic.edu.au
      IT Lecture notes: http://vceit.com
      Moderator: IT Applications Mailing List



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    IT Applications Mailing List kindly supported by 
    http://www.vcaa.vic.edu.au/vce/studies/infotech/infotechindex.html - Victorian Curriculum and Assessment Authority and 
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  -- 
  Mark Kelly
  Manager - Information Systems
  McKinnon Secondary College
  McKinnon Rd McKinnon 3204, Victoria, Australia
  Direct line / Voicemail: 8520 9085
  School Phone +613 8520 9000
  School Fax +613 9578 9253
  kel at mckinnonsc.vic.edu.au

  Webmaster - http://www.mckinnonsc.vic.edu.au
  IT Lecture notes: http://vceit.com
  Moderator: IT Applications Mailing List


  _______________________________________________ 
  http://www.edulists.com.au - FAQ, resources, subscribe, unsubscribe 
  IT Applications Mailing List kindly supported by 
  http://www.vcaa.vic.edu.au/vce/studies/infotech/infotechindex.html - Victorian Curriculum and Assessment Authority and 
  http://www.vitta.org.au - VITTA Victorian Information Technology Teachers Association Inc
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