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  1. #1
    Join Date
    Sep 2006
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    18

    Help on ERD:Database about Auctions

    I'm trying to solve an exercise(studying for an exam) concerning auctions and the text is as following:

    An auction organization does auctions of various product and wants to have a database that stores all the necessary information to it's appropriate functioning.
    In each auction there's a couple of products available for sale.Those products are only put for sale if they are in great conditions.Only people who registered can participate in an auction.In an auction, a person can make many licitations.Each licitation get's registered as an unique identifier.A licitation referes always to one product that was for sale in an auction.At the end of the auction the licitated products are sold to the person whose liciattion value was the highest.We want to store the information about the date,value of the sale and type of payment.

    Some of the attributes to register are the following:
    Id_person, name,identity card,address;id_auction,date,place of auction; id_product,designation,type and base value;id_licitation and value of licitation;id_sale,value, date of sale and type of payment.

    I need some help on this,and this's what I've came so far(see attachment).
    Also I have a question: in what cases should we use a ternary relationship?

    Thanks in advance for all the help!
    Attached Thumbnails Attached Thumbnails bd er.JPG  

  2. #2
    Join Date
    Sep 2006
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    18
    Can anyone help me?

  3. #3
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    A ternary relationship simply implements a many-to-many join between three tables.
    URL for unauthorized site removed
    Last edited by blindman; 12-19-06 at 10:43.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  4. #4
    Join Date
    Apr 2002
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    Toronto, Canada
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    btw, joe celko has nothing to do with that site (i asked him about it)

    anything attributed to joe celko on that site has been plagiarized

    i wouldn't aid/abet their ad-revenue-generating efforts by linking to them
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  5. #5
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
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    Quote Originally Posted by r937
    btw, joe celko has nothing to do with that site (i asked him about it)

    anything attributed to joe celko on that site has been plagiarized

    i wouldn't aid/abet their ad-revenue-generating efforts by linking to them
    I wondered about that when I say the site. URL deleted!
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  6. #6
    Join Date
    Sep 2006
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    18

    ...

    Thank you for the explanation!And what about my er diagram?Does it look ok based on the exercise specifications?

  7. #7
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    Its scribbled on a freakin' napkin!
    You want us to decipher scrawlings that you would not even submit to your professor?
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  8. #8
    Join Date
    Sep 2006
    Posts
    18

    ...

    No,it's not scribbled on a freakin napkin.That's the way we usually draw our diagramas on classes and that's the way the professor usually draw his diagram on classes.But I think I can do a better diagram that can look a bit more clean.

  9. #9
    Join Date
    Sep 2006
    Posts
    18

    ...

    Here's the better version of my er...Sorry for the other bad quality version...I hope this new one looks ok...Any help is much appreciated!
    Attached Thumbnails Attached Thumbnails auction er.JPG  

  10. #10
    Join Date
    Sep 2006
    Posts
    18

    ...

    Is my er diagram ok?

  11. #11
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    We don't do homework. We are not going to go through your assignment requirements and then check your work for you.
    If you have a specific question, we will do our best to answer it.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  12. #12
    Join Date
    Sep 2006
    Posts
    18

    ...

    Well,specifically, I wanted to know if the ternary relationship looks ok as it isconsidering the information provided by the text.

  13. #13
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    I haven't read your assignment and I'm not going to, but the diagram looks fine to me.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

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