The symbol → indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE?

(X,Y) → (Z,W) implies X → (Z,W)
(X,Y) → (Z,W) implies (X,Y) → Z
((X,Y) → Z and W → Y) implies (X,W) → Z
(X → Y and Y → Z) implies X → Z

Correct answer: (X → Y and Y → Z) implies X → Z

Solution

This statement is an application of the transitive property of functional dependencies, which states that if one attribute functionally determines a second, and that second attribute functionally determines a third, then the first attribute must also functionally determine the third.

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