the term of the relation as performed by combining the tuples from one
relation with those a second relation to produce a third
relation.duplicate tuples are eliminated.the the relation must be union
the difference of two relations is a third relation having tuples that occur in
the first relation but not in the second relation.
the intersection operation selects the common tuples from the two relations.
the cartesian product of two relations is the concatination of tuples belonging
to the two relations.a new resultant scheme is created consisting of
concatination of all possible combination of tuples.