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  1. #1
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    Jun 2014
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    9
    .................................................. ..........
    Last edited by hellodt; 07-02-14 at 22:23. Reason: Unrelated queries

  2. #2
    Join Date
    Jun 2014
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    9

    normalisation scenario

    Hi any one have any idea where my normalisation of dataset below has went wrong?

    I want to be able to enter a value in Field4 after tables 1 to 3 are complete but before Table 4 is complete which my normalised tables won't allow.

    Dataset

    Field1
    Field2
    Field3
    Field4
    Field5 (PK)
    Field6 (PK)
    Field7(PK)
    Field8


    Normalisation of dataset to 3NF:

    TABLE1 Field5 (PK), Field1

    TABLE2 Field6 (PK), Field2

    TABLE3 Field7 (PK), Field3

    TABLE4 Field5 (PK), Field6 (PK), Field7 (PK), Field8, Field4


    Notes:

    Fields 2 & 6 are similiar attributes

    Fields 3 & 7 are similiar attributes

    Fields 1-3 would effectively be a PK for Field 4

  3. #3
    Join Date
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    If Field 4 is NULL-able, then it can't be part of a relational key.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  4. #4
    Join Date
    Jun 2014
    Posts
    9

    further info

    Thanks for your reply Pat.

    Field 4 is not a key:

    What I was saying is that Fields 1 to 3 (if they were in the same table) would create a PK for Field 4.

    The scenario is that:

    The data in Tables 1 to 3 may effectively be entered some time before data in Table 4 is completed

    The business process must though allow for Field 4 value to be entered immediately after Tables 1 to 3 data is provided.

    My Normalised Tables would not allow for this second point:

    Wondering where in the normalisation steps (to 3NF) I have went wrong?

  5. #5
    Join Date
    Jun 2014
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    9
    ............................
    Last edited by hellodt; 07-02-14 at 22:24. Reason: Tidying up thread

  6. #6
    Join Date
    Jun 2014
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    9

    reply

    Don't think your reply helps with my "Normalisation Scenario" Pat

    Can any one else help?

  7. #7
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    In front of the computer
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    Make Columns 1-3 PKs (Primary Keys) in their own tables, and also FKs (Foreign Keys) into Table 4, and make the combination of Columns 1-3 be the PK for Table 4. When you add a row to Table 4, supply the values for Columns 1-3.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  8. #8
    Join Date
    Jun 2014
    Posts
    9

    steps

    Thanks.

    So by following the normalisation steps will it not always give me the table makeup I need? Or does it suggest I did something incorrect in the process?

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