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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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