Define multivalued dependency, Database Management System

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Define multivalued dependency.  What do understand by trivial multivalued dependency? 

Ans: A multivalued dependency is a full constraint among two sets of attributes in a relation. It is differ to the functional dependency, the multivalued dependency needs that certain tuples be present in a relation. Hence, a multivalued dependency is a unique case of tuple-generating dependency. The multivalued dependency plays an important role in the 4NF database normalization.

An MVD X→→Y in R is known as a trivial MVD if (a) Y is a subset of X or (b) X U Y = R


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