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vijay
candidate key,
November 5, 2008 at 10:34 PM

let me clear this rekha....
always there is a small confusion between various keys used in the dbms but there is a simple classification on behalf of which we can distinguish between them.


CANDIDATE KEY :-


It is the one through which we can uniquely identify each tuple of the relation, there could be two possibilties that either the canditate key could be
a)CANDIDATE KEY with one attribute such as {employee_id} can do so.
b)or CANDIDATE KEY with a combination of the two attributes {employee_name,employee_city}.


These both can easily do so (uniquely identify) but problem occurs when question arises can we make a combination of those two attributes one out of which cna easily perfom the task of uniquely identifying the each tuple of the relation.


such as for ex:-
we can not make a combination of


{employee_id ,employee_name}


because out of these two attributes combination, the attribute


{employee_id}


could singly can perform these task as well therefore we can not a canditate key as a combination of those two attributes one out of which can alone uniquely identify the tuple in a relation.


this was all about the candidate key if then also u have any problem regarding these key u can contact on my email add :-vijay.daultani@gmail.com
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