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