Question

Consider the relation R with the following functional dependencies:
R(P,Q,R,D,E,F)
FD = {P →Q,QR → D, E → RD → P}
Which of the following are the candidate keys?
(a) PF, QF.
(b) PF, QF, RF
(C) PEF, QEF, DEF
(d) PEF, QFR​

Answer 1

Answer:

pf,qf.

Explanation:

Answer 2

Option d) PEF, QFR​

The relation R with the following functional dependencies:

R(P,Q,R,D,E,F)

FD = {P →Q,QR → D, E → RD → P}

The candidate keys PEF, QFR​

• A candidate key is a single key or a collection of keys that collectively and specifically identify rows in a database. A Candidate key is a subset of Super keys and is free of any extraneous characteristics that are not necessary for tuple identification.
• Primary key and candidate key have the exact same meanings. The same goal of all potential keys is to safeguard data integrity by avoiding data duplication. If more than one candidate key needs to be enforced in a table to ensure some data is not duplicated, it is totally reasonable.
• In other words, if ABC is a candidate key, neither A, B, or C, or any of their combinations, can be a super key. As a result, we can say that a candidate key is a minimal collection of attributes of a R(Relational Schema) that may be used to uniquely identify a tuple of a table.

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