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4 Answers

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Maximum is 20 and minimum is also 20.

If there is no match, So 20 Unmatched rows from R is returned.

If 10 rows are matched , 10 matched rows and 10 unmatched rows will be returned.
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20.... Since the primary key of r2 is referred in r1 so all the tuples in the r1 will come.... If there had not been left outer join and only natural join is present then also the answer would be 20.... There is no case of maximum or minimum here..... Here for both the max and min the answer will remain same ie 20....
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in any type of join operation the maximum number of tuple is  M x N 

here answer would be 20 x 10 = 200 tuples

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20 tuples.

In Left Outer Join, beside the tuples satisfying join condition of both tables, the remaining left(First) table with non satisfying join condition tuples from first table would also be selected from the database, however, the attributes for second table would be represented as NULL in these tuples.

In best case: All 10 tuples of r2 inner join with r1 are selected, along with remaining 10 tuples of r1 .

In Worst case : 0 tuples of r2 are selected,along with 20 tuple of r1(with Null for joined r2 attributes) .

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Gupta731 asked Oct 24, 2018
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C is provided as the answer. Statement P, I understand but why S is also correct?