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From:Peter Brawley Date:April 14 2005 7:24pm
Subject:Re: Database design question
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Mahmoud,

>Are these values atomical?

>My other question is what are the repercussions of 
>not putting a table in 2nd and 3rd Normal Form.

Your 'choice1-subchoice1' etc are combined values, so they aren't 
atomic. From your three example dropdown values, it looks as if 'choice' 
and 'subchoice' have a many-to-many relationship, and if that's so,  
you'll probably need a second table for 'subchoice' and a third table to 
store combinations of choice and subschoice.

There are examples of disadvantages of  not putting a table in 2NF or 
3NF at http://www.artfulsoftware.com/mysqlbook/sampler/mysqled1ch01.pdf, 
click on 'Normalisation and the normal forms', & read the sections on 
1NF, 2NF and 3NF.

PB

-----


Mahmoud Badreddine wrote:

>Hello,
>I have two questions:
>I would like to know whether I am violating the principle of atomicity in 
>doing the following:
>
>I have a form which has a field with the following options: Choice1, choice2 
>and choice3.
>Each of the above choices have two further subchoices : subChoice1, 
>subchoice2.
>
>so in my form I have a pull-down list and these are the choices I have:
>choice1-subchoice1
>choice1-subchoice2
>choice2-subchoice1
>....
>....
>and so on.
>
>Are these values atomical?
>
>My other question is what are the repercussions of not putting a table in 
>2nd and 3rd Normal Form.
>Thank you.
>
>
>  
>
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Thread
Database design questionMahmoud Badreddine14 Apr
  • Re: Database design questionPeter Brawley14 Apr