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   comp.databases.ms-sqlserver      Notorious Rube Goldberg contraption      19,505 messages   

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   Message 19,156 of 19,505   
   Tony Johansson to All   
   Problem with E-R model   
   06 Feb 15 18:40:44   
   
   From: johansson.andersson@telia.com   
      
   This is a question about horse jumping.   
      
   I have these relations one Rider can have many horses but one horse can only   
   be owned by one rider.So here we have one to many counted from the Rider   
   side.   
      
   One Rideclub can have many member which is Riders but one Rider can belong   
   to only one RideClub. So here we have one to many counted from Rideclub   
      
   One Rider can participate in many classes and one class can have many Rider   
   so here we have many to many.   
      
      
   For example   
   Nisse Hult owns the two horses Trisdan and Sylfid.   
      
   In my current E-R design I can tell which horse the Rider is using in a   
   special class I can only know that Nisse Hult is using any of the horses   
   that he owns.   
      
   If I for example change the conditions so that I have one to one relationhip   
   between Rider and Horse that will solve the problem   
   because if Hisse Hult is starting in a class he owns only one horse.   
      
   The other solution is that I can create a new table with is the contents of   
   Horse and Rider and then remove the  Horse and Rider.   
   But if I do so I get a lot of double information as you can see here.   
   So if I do this I can see directly which horse Nisse Hult is using becuse   
   the Id will be put in the relation table in between   
   Rider and Class   
      
   Id   social sec number        Rider          Horse       ImgHorse   
   DescHorse               ImgRider              RiderDesc          Phone   
    1  123456-0001               NisseHult   Trisdan    ImgTrisdan    Info   
   about Trisdan     img Nisse Hult   Info Nisse Hult   123 45   
    2  123456-0001               NisseHult   Kitty        ImgKitty        Info   
   about Kitty        Img Nisse Hult   Info Nisse Hult    123 45   
      
   I hope you can understand what I'm trying to say.   
      
   So what is the best solution if I want to know which Horse the Rider is   
   starting with in a Class?   
      
   //Tony   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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