Does anybody have some theoretical idea about functional dependencies.
I have to find non redundant covers and convert a relation to BCNF. But i am unable to understand the concept.
My question is:
Consider the following relations and the set of Function Dependencies(FDs):
SHIPMENT (ship_id, S_capacity, S_date, cargo, amount)
FDs are as follows:
Ship_id, S_date --> cargo
Cargo, S_capacity --> amount
Now perform the following:
(i) Identify the key of the relation.
(ii) Find the non-redundant cover of the given FDs.
(iii) Normalize the relation into BCNF. Is the decomposition dependency preserving? Give reason for your answer.
Yes... Thanks all....
Finally I found it myself...... though it was difficult to understand from books...
(i) Key for the relation is (ship_id,s_date) because there does not exist any dependency as R-->key for key being a proper subset of R+. and all attributes are dependent on the key.
(ii) None of the given dependencies is redundant. So, non redundant cover for the dependency set is (Ship_id -->S_capacity;Ship_id, S_date --> cargo;Cargo, S_capacity --> amount)
(iii)Converting to the BCNF gives the following three relations for breakup of the given one: