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 Posted by Jack Vamvas on 03/04/07 09:36 
Assuming you aren't repeating data in TRANSPORTATION_ITEM then you are  
already satisfying one of the normalisation principles.i.e minimising  
redundancy. 
Even though what you are doing in TRANSPORTATION_ITEM will work, I would  
separate into 2 tables with distinctive names for the tables. 
 
 
--  
 
Jack Vamvas 
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<bbcrock@gmail.com> wrote in message  
news:1172984454.273489.90110@s48g2000cws.googlegroups.com... 
>I have three tables with a relationship I've never worked with 
> before.  Can anyone suggest/comment on the best way to create a third 
> normal form relationship between these tables? 
> 
> The tables basically are: 
> 
> TRAIN (TRAIN_ID and 15 columns about train specs, etc) 
> TRUCK (TRUCK_ID and 12 columns about truck specs, etc) 
> TRANSPORTATION_ITEM 
> This table has, among others, two columns, TRUCK_ID and TRAIN_ID.  If 
> the truck column is used there can be no data in the train column and 
> vice versa. 
> 
> This relationship seems denormalized to me, but I don't remember how 
> to normalize it.  Does anyone know the correct name for this kind of 
> relationship? 
> 
> thanks! 
>
 
  
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