Aspire's Library

A Place for Latest Exam wise Questions, Videos, Previous Year Papers,
Study Stuff for MCA Examinations - NIMCET

Previous Year Question (PYQs)

In a schema $R(A, B, C, D, E, F, G, H)$, each field of $R$ contains only atomic values.
$F = {CH \rightarrow C, A \rightarrow BC, B \rightarrow CEH, E \rightarrow A, A \rightarrow EFG}$ is a set of functional dependencies so that $F^+$ is exactly the set of FDs that holds $R$. The relation $R$ is :




Solution

Given FDs


$CH \rightarrow C$

$A \rightarrow BC$

$B \rightarrow CEH$

$E \rightarrow A$

$A \rightarrow EFG$


From


$A \rightarrow BC$

$A \rightarrow EFG$


we get


$A \rightarrow BCFG E$


Then


$B \rightarrow CEH$


Thus


$A^+ = {A,B,C,D,E,F,G,H}$


So $A$ is a candidate key.


Now check dependency


$E \rightarrow A$


Since $E$ is not a superkey, but RHS contains a prime attribute, it satisfies 3NF but violates BCNF.


Therefore the relation is


in 3NF but not in BCNF.


Online Test Series,
Information About Examination,
Syllabus, Notification
and More.

Click Here to
View More

Online Test Series,
Information About Examination,
Syllabus, Notification
and More.

Click Here to
View More
Ask Your Question or Put Your Review.

loading...