satisfies algorithm -
07-25-2008
, 07:41 AM
Hi all,
the following is the algorithm which i saw in schaum series
book(fundamentals of relational databases)
satisfies algorithm
this algorithm shown below can be used to determine if a relation r
satisfies or does not satisfies a given functional dependency A -> B.
the input to the algorithm is a given relation r and a functional
dependency A -> B. the output of the algorithm is true if r satisfies
A -> B; otherwise the output is false.
1) sort the tuples of the relation r on the A attribute(s) so that
tuples with equal values under A are next to each other
2) check that tuples with equal values under attribute(s) A also have
equal values under attribute(s) B
3) if any tuples of r meet condition 1 but fail to meet condition 2
the output of the algorithm is false. otherwise, the relation
satisfies the functional dependency and the o/p of the algorithm is
true.
now my question is there any other better method (other than inference
axioms) ? |