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  1. #1
    Join Date
    Mar 2006
    Posts
    36

    Question Unanswered: How to remove 1:1 Relationships

    I have an asset schema problem which I'm not too sure how to resolve....

    I have an asset table which stores values common to all asset types. I have created seperate asset type tables(VehicleAssetDetail, PropertyAssetDetail, InvestmentAssetDetail) to store their specific details.

    This in turn creates 1:1 relationships between "Asset" table and the respective detail tables.

    If I were to store all the details in the "Asset" table it would cause a lot of redundancy bearing in my mind there are about four other asset type details I have excluded from the schema.

    Are the 1:1 relationships bad? If they are, how do I resolve them without throwing all the columns from the asset details tables into the Asset table?

    Attached is a 15Kb gif image of the schema. I'd really appreciate any help with this...
    Thanks.
    Attached Thumbnails Attached Thumbnails schema.gif  

  2. #2
    Join Date
    Nov 2002
    Location
    Jersey
    Posts
    10,322
    A lot of your assertions are fals.

    Why would a 1:1 create redundant data?

    Only reason I would use a 1:1 is if the row length is too long, then I would catergorize the data into appropriate entities.

    But remember, the best join, is none
    Brett
    8-)

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    The physical order of data in a database has no meaning.

  3. #3
    Join Date
    Mar 2006
    Posts
    36
    Hi Brett...
    You may have misunderstood my statement...
    If all the columns of each Detail table would be placed in the "Asset" table and the Details tables dropped, most of the columns in the "Asset" table would be null, except for the columns which relate to the specific asset which is inserted.

    A 1:1 relationship would not create redundancy.
    So back to my original question....

  4. #4
    Join Date
    Jan 2007
    Location
    UK
    Posts
    11,434
    Provided Answers: 10
    This was raised in another thread which may be worth a read

    http://www.dbforums.com/showthread.php?t=1622324

    Read the last 3 or 4 posts or so and you'll get the answer
    George
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