What do you understand by functional dependency and transitive dependency in DBMS?

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chetan shidling asked 4 years ago

I need short information.

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chetan shidling answered 4 years ago

Functional Dependency

A functional dependency is a constraint that is used in describing the relationship among different attributes in a relation.

Example:

Consider a relation “A1” having attributes X and Y. The functional dependency among these two attributes will be:
x->Y

Transitive Dependency

A transitive dependency is a constraint which can only occur in a relation of three or more attributes.

Example:

Consider a relation “A1” having attributes X, Y, and Z. Now, X->Z is said to hold transitive dependency, only if the following functional dependencies holds true:
X->Y
Y doesn’t -> X
Y -> Z