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Generalize & specialize design

  • November 14, 2008 at 2:10 am

    #195799

    Hi guyz,

    I was a newbie in database design.

    currently i was trying to separate an item entity attribute to different specific entity so i can store some special attribute according different type of item.

    Basically i have diagram on how i going to implement this database, but was having problem using one foreign key to transitive dependence on four primary key

    HEre was my diagram design :

    Note :

    Typeid was book, music, movie or games

    While the indexno will keep increment.

    Was this the correct way to generalize same attribute under the item entity and specialize the specific attribute to different type entity? or there is some better way to do so, please advice.

    Thanks

  • November 16, 2008 at 1:42 am

    #899052

    There is seldom one "correct way" to do things but the potential advantage of this design is that you can easily enforce the rule that each item only has one subtype. Similar example at:

    http://blogs.conchango.com/davidportas/archive/2007/01/08/Distributed-Keys-and-Disjoint-Subtypes.aspx

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