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  1. #1
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    Desperate ERD Help!

    Hi


    Basically Im having trouble with an Entity Relationship Diagram (ERD), for an assignment. The ERD is based on a simple scenario, I have attempted it a few times and the lecturer says its not right.
    Last edited by JIM1974; 10-21-07 at 11:13.

  2. #2
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    what's wrong with the part in red, in your own words?

    where are your constraints? (primary keys and foreign keys)
    rudy.ca | @rudydotca
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  3. #3
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    HI There

    Thanks for taking a look.

    Below is a link to a updated erd with all the attributes and primary/foreign keys.
    Last edited by JIM1974; 10-21-07 at 11:13.

  4. #4
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    Quote Originally Posted by JIM1974
    ... she was not happy with the skilled vehicle drivers entity
    neither am i

    in words, what does one instance of this entity represent? what is that pk made of? it looks like it might be an auto_increment, and generally speaking, you should never have an auto_increment for a relationship table

    see what you can do if that table were completely eliminated
    rudy.ca | @rudydotca
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  5. #5
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    Hi Again

    sorry about the basic diagram dont have access to proper ERD design tool at home.
    Last edited by JIM1974; 10-21-07 at 11:14.

  6. #6
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    One would think that colleges could sure come up with better real life examples to model. ..driver skill?? I personally don't see where that ties into an order.

  7. #7
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    fjm1967

    Do you have any sudgestions?
    Basically i just want a quick solution so i can get the schema finished and build for oracle database and get the assisgnment out the way.
    Last edited by JIM1974; 10-21-07 at 09:24.

  8. #8
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    I can give you my opinions about your model but r937 is the one you want to listen to.

    Do you have the option of totally removing the skill entity or did your instructor tell you that you had to have it? I don't understand what driver skill has to do with an order.

  9. #9
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    Basically the instructor gave the scenario and the entitys



    Then we have to come up with a working model

    But i would be happy for any input you could offer me.

    I do appriciate time given.
    Last edited by JIM1974; 10-21-07 at 11:14.

  10. #10
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    Ok, I will give you my take on how it should be based on what your instructor said. brb.

  11. #11
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    This is how I would model it. I would remove the three entities you have for the special vehicles. You can use the vehicle type column in the vehicle entity to track that.

    particular skills are not necessarily associated with a vehicle, however; the drivers’ skills information is used merely as a guide to driver allocation at present.
    Because of this, I simply associated the chauffer's skill set with the driver. I am assuming that the "skilled vehicle driver" entity is only a record of the skill levels that a driver can have.
    Attached Thumbnails Attached Thumbnails export.jpg  

  12. #12
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    Quote Originally Posted by JIM1974
    Basically i just want a quick solution
    you are not going to get that here

    we do not do homework assignments

    however, we will help you do yours by asking you questions

    you still have to do all the work, though
    rudy.ca | @rudydotca
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  13. #13
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    oops.. I missed that..

  14. #14
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    Cheers fjm1967

    I understand your solution to the scenario.

    Does anybody else agree or disagree with fjm1967 opionion's to my model or anythink else they can add.

    r937 what do you think?

  15. #15
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    Cool thats fine with me.
    Ive been at it for 3 weeks and i was only really asking for asistance, I learn through examples and this is the first one ive attempted.
    In my oppion data modeling is not clear cut. Its more on the oppions of erd designer. That is basically what i was asking for.
    Last edited by JIM1974; 10-21-07 at 10:14.

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