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  1. #1
    Join Date
    Aug 2013

    Unanswered: some Database Questions

    Hi guys,

    Need help answering the following questions. Have a presentation to do and any info will help. I appreciate any help.


    1.What key mathematical property of a field is used in deciding if it should belong to an index?

    2. What is the general class of dependencies which uniquely identify every record in a table?

    3.You are given a table (A, B, C) where A is a low-cardinality attribute, B is a high-cardinality attribute, C is a numerical variable. You're asked to produce cross-tabulation of sum of C by both A and B and show resultant table in Excel spreadsheet. Would you choose to show A as columnar dimension? Why?

  2. #2
    Join Date
    Feb 2004
    In front of the computer
    Provided Answers: 54
    1. Divisibility by at least one prime number. If a number is not evenly divisible by at least one prime, it will be very difficult to index.
    2. Database 101 is the class that covers the dependancies for uniquely identifying every tuple, and by extension every record in a file.
    3. Yes, because it will minimize the number of rows in the result set which makes the Excel spreadsheet easier to use.
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

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