Lectures / LECTURE 3
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Transitive dependency example
•Suppose we had the following table storing information about cars and their owners.
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Transitive dependency example
•Suppose the PK of the previous table was owner id.
•Also suppose the relation had the following functional dependencies:
Owner id -> {name, car id, make, model} Car id -> make, model
•This relation contains a transitive dependency because owner id -> car id -> {make, model}
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Example 1 without errors
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Example 2 without errors
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Books
•Connolly, Thomas M. Database Systems: A Practical Approach to Design, Implementation, and Management / Thomas M. Connolly, Carolyn E. Begg.- Fifth.- United States of America: Pearson Education, 2010
•Garcia-Molina, H. Database system: The Complete Book / Hector
Garcia-Molina.- 2.- United States of America: Pearson Prentice Hall, 2009
•Sharma, N. Database Fundamentals: A book for the community by the community / Neeraj Sharma, Liviu Perniu.- First Edition.- Canada, 2010
Question
The FD X -> Y is a full dependency in a relation R, if there is _____ attribute A that can be _____ X and the dependency still holds.
a)At least one, added to
b)No, added to
c)No, removed from
d)At least one, removed from
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Question
The FD X -> Y is a partial dependency in a relation R, if there is _____ attribute A that can be _____ X and the dependency still holds.
a)At least one, added to
b)No, added to
c)No, removed from
d)At least one, removed from
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