Natural join

Question

My answer is not matching with any of the option.so what is the correct answer 

Comments

@Panda except the first tuple in the box other would not be there in resulting table ! answer should be $0,120$

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What will be the values ?

No common attribute, max : 120*8  min = 120*8 (Cartesian Product)

Common attribute (But no foreign key constraint) : max : 120  min : 0 

Common attribute (Foreign key constraint given) : max : ? min : ?

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joshi_nitish Ok you are right. If there is no mention of referential integrity we should not assume it already.

Answer 1

min=0 will occur when there is some common attribute, but that common attribute does not contain any value which is common in both tables.

for the maximum let all the values of C in R is same means 120 values are same so from R to S there will 120 tuples matches(for any single tuple of S as in R all values of C are same)

min =0 , max =120

Comments

 min = 0 and max = 120 x 8 => 960 

maximum number of tuple in natural join is M x N 

proof – https://stackoverflow.com/questions/30145583/what-is-maximum-number-of-tuples-in-natural-join/30145769