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Discussion on normalization

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• Which is better ? 3NF or BCNF ???
  • Neither !!!

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  • There is another important criteria that we want to achieve in database design:

    Preserve functional dependencies !!!

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  • Properties of 3NF:

    It is always possible to obtain a 3NF design that is: Lossless        Preserves all functional dependencies

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  • Properties of BCNF:

    A BCNF design: Is guaranteed to be lossless        But may not preserves all functional dependencies !!!

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• Goal of normalization
  • Ultimate goal:

    BCNF Lossless Preserves all functional dependencies

    If the BCNF decomposition does preserves all functional dependencies, then we are done

    Otherwise....

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  • The next ultimate goal:

    3NF Lossless Preserves all functional dependencies

    This is always achievable

    However:

    Not using the technique that we have studied.....