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  1. #1
    Join Date
    Nov 2013

    Question database normalisation

    Hi everyone,

    I was studying for my final exam and I got up to a point where I didn't know how to answer a question.

    I have a table in unnormalised form with attributes: branch, branchAddress and telephoneNo.
    I wanted to make it in third normal form, and I have no idea how to deal with the telephone attribute. Branches could have multiple phone numbers.
    Would you happen to know how I should what I should do??


  2. #2
    Join Date
    Feb 2004
    In front of the computer
    Branches can have many phone numbers, and it is also possible for a phone number to have many branches (think of a shared incoming toll-free number).

    To handle a branch with many phone numbers, just create a telephone number table which contains the branch as a foreign key.

    To completely solve the problem allowing a many-to-many relationship between branches and phone numbers you'll need to add a linking table that holds the foreign keys from both the branch and the phone number tables.

    I'd recommend including the starting and ending dates in either case, since phone numbers do change over time!

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

  3. #3
    Join Date
    Nov 2013
    Thank you for your help PatP, your first solution is what I was looking for.

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