Consider relation ‘R’ and ‘S’ have ‘n’ and ‘m’ tuples, respectively. Choose the best matching between List-I (Expression) and List-II (Maximum number of tuple):
Soln. According to me Answer should be Option C.
1.R union S = m+n (easy nothing to say)
2. Say Relations are like:- R(A,B,C) s(C,D)
A B C C D
1 2 3 3 4
2 3 3 3 5
4 3 3 3 6
Now in R natual join S = m * n
So option C should suffice isn't it ?
Verma Ashish yes right !!
see the ( ) on Relation R
ist it just execute selection condition on R then it does cartesian product
d is Right answer
. P- 4 is obvious so no need to explain this.
Q – 3 because natural join compare the common attribute so the best case would be- all of matches the condition and combine min(m,n) since all tuples are matching extra number of tuples in either of relation will be discarded
R – 2 explanation - because for maximum number of tuple the best case would be – that all tuples in R satisfy the given condition and then got cross product with S and we know that number of tuples in cross product m x n
S – 1 the best case for maximum tuples would be if nothing get minus or discarded from relation R with n tuples so max tuples = n
No correct option.