Suppose ORACLE relation R(A, B) currently has tuples {(1, 2), (1, 3), (3, 4)} and relation S(B, C) currently has {(2, 5), (4, 6), (7, 8)}. Consider the…
Suppose ORACLE relation R(A, B) currently has tuples {(1, 2), (1, 3), (3, 4)} and relation S(B, C) currently has {(2, 5), (4, 6), (7, 8)}. Consider the following two SQL queries SQ1 and SQ2 :
SQ1 : Select *
From R Full Join S
On R.B = S.B;
SQ2 : Select *
From R Inner Join S
On R.B = S.B;
The numbers of tuples in the result of the SQL query SQ1 and the SQL query SQ2 are given by :
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Correct answer: (D) 4 and 2 respectively
Explanation
R.B = S.B holds for 2 records (B = 2 and B = 4), so SQ2 (inner join) returns 2 tuples. The full outer join returns the 2 matching tuples plus the unmatched tuple of R (1, 3) and the unmatched tuple of S (7, 8), so SQ1 returns 4 tuples.