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  1. #1
    Join Date
    Nov 2011
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    2

    Question Normalization with no functional dependencies

    Hey guys,

    I'm currently doing a databases subject at university and I'm studying for my exam. I've been looking through past exams (which all feature a decent amount of normalization), and I'm stuck on one of the questions.

    The question simply asks me to find the highest normal form of a schema - no actual normalization is required.

    The schema is called Transaction and it has three attributes: buyerId, ownerId and propertyId. The schema contains no functional dependencies.

    Because the schema contains no functional dependencies, would you say that it doesn't have a primary key, and therefore does not satisfy 1NF, or could it be said that the primary key is a composite key that is composed of all the attributes (which satisfies 1NF)?

    In the latter case, it would satisfy 2NF as there are no partial dependencies, and it would satisfy 3NF as there are no transitive dependencies. The determinant is a candidate key (you can't remove any attributes from it), so the schema would seem to be in (at least) BCNF.

    What are your thoughts? Am I going about this in the wrong way?

    Thanks in advance,
    Chris

  2. #2
    Join Date
    May 2008
    Posts
    277
    Quote Originally Posted by chrisparton1991 View Post
    Because the schema contains no functional dependencies, would you say that it doesn't have a primary key, and therefore does not satisfy 1NF
    No. Think of your most basic many-to-many intersection table, or your most basic lookup table. Do they have any functional dependencies? Do they have a primary key?

    or could it be said that the primary key is a composite key that is composed of all the attributes (which satisfies 1NF)?

    In the latter case, it would satisfy 2NF as there are no partial dependencies, and it would satisfy 3NF as there are no transitive dependencies. The determinant is a candidate key (you can't remove any attributes from it), so the schema would seem to be in (at least) BCNF.
    This is the right direction. Not sure which normal forms you've all covered, but if you go through their definitions, like you have here, then you shouldn't have any problems arriving at the correct answer.

  3. #3
    Join Date
    Nov 2011
    Posts
    2
    Thanks for the quick reply. I had a feeling it wouldn't be as simple as "it doesn't satisfy 1NF."

    We've covered up to 5NF in lectures, but the lecturer only expects us to decompose until we arrive at BCNF, so I can stop there.

    Cheers,
    Chris

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