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A functional dependency f on R is _______by a set of functional dependencies F on r if every instance of r(R) that satisfies f also satisfies F.(a) Logically Defined(b) Logically Derived(c) Logically implied(d) None of the mentionedI have been asked this question in an interview for job.The origin of the question is Functional-Dependency Theory in chapter Relational Database Design of RDBMS |
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Answer» CORRECT choice is (c) Logically implied To explain: Given a set F of functional dependencies on a schema, we can PROVE that certain other functional dependencies also hold on that schema. We SAY such FDs are logically implied by F. A functional DEPENDENCY f on R is logically implied by a set of functional dependencies F on r if every instance of r(R) that satisfies F also satisfies f. |
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