Question

Choose a right statement to describe about functional dependency.

Select one:
a. all of others
b. constraints between two sets of attributes of a relation
c. a functional dependency is written like X->Y
d. A set of attributes X (A1,A2,..,An) in R determines another set of attributes Y also in R if and only if each X value is associated with precisely one Y value.

Answer 1

A functional dependency is a constraint between two sets of attributes of a relation, represented by X->Y. X determines Y, but Y does not necessarily determine X.

Step-by-step explanation:

A functional dependency is a constraint between two sets of attributes of a relation. It is represented by a statement like X->Y, where X is a set of attributes that determines another set of attributes Y. This means that for every value of X, there is precisely one value of Y associated with it. However, the relationship between X and Y is not necessarily symmetrical, meaning that Y is necessary for X, but X is not necessary for Y. In other words, X is always sufficient for Y.