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Thread: Erd

  1. #1
    Join Date
    Aug 2007
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    Auckland New Zealand
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    Erd

    Im trying to design a Logical Schema for a DB Design, I expect the DB to grow to a very large size, so I need to find the best possible design.

    1. An Advertisement is charged a Fee always.
    2. An Event is Charged a Fee if the listing is made by a Profitable Organization.

    3. A Profitable Organizations Listing is charged a Fee.
    4. All Fees are Charged to Accounts.

    I Have used three associative entities, Listing_Fee, Event_Fee, and Ad_Fee, is this an OK design solution, are the joins a concern. I used this setup as opposed to a single table for all three, because each row, will always omit two other columns, (int* 2) * Number of Records, This cold be a Huge Number, and large amount of redundant space.

    Any Comments Appreciated.

  2. #2
    Join Date
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    three associative tables is okay, yes, assuming you have three many-to-many relationships

    i have a hard time believing a fee is an independent entity in its own right, though

    that's like having an ecommerce site which has products for sale, and setting up a Price table, so that each row is a separate price, and then setting up an association table to products...
    rudy.ca | @rudydotca
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  3. #3
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    Aug 2007
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    Its not exactly its own entity, it sits as ad_fee between an advertisement and the Account. So [PKFK] AD_ID and [PKFK] Account_ID. I Was thinking I could Assign the Price too the Associative Entities, so There will be an individual record of each charge (As there will be one for each time period). Or Should I use an Invoice or Something else?

  4. #4
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    i have no idea, sorry

    i don't have your understanding of the business requirements
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  5. #5
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    There will be a fee charged for each of the entities, based on a time period, month or year. To charge them How would you do it, would you use a Invoice for each individual fee.

  6. #6
    Join Date
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    i have no idea, sorry

    i don't have your understanding of the business requirements
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  7. #7
    Join Date
    Dec 2003
    Location
    Canada
    Posts
    710
    Nate, if you could explain your application more thoroughly we might be able to help you.

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