Database table by name Loan_Records is given below. Borrower Bank_Manager…
2011
Database table by name Loan_Records is given below.
Borrower | Bank_Manager | Loan_Amount |
Ramesh | Sunderajan | 10000.00 |
Suresh | Ramgopal | 5000.00 |
Mahesh | Sunderajan | 7000.00 |
What is the output of the following SQL query?
SELECT count(*) FROM ( SELECT Borrower, Bank_Manager FROM Loan_Records) AS S NATURAL JOIN (SELECT Bank_Manager, Loan_Amount FROM Loan_Records) AS T );
- A.
3
- B.
9
- C.
5
- D.
6
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Show answer & explanation
Correct answer: C
Correct result: 5.
Explanation: The two subqueries both include the column Bank_Manager, so NATURAL JOIN matches rows on Bank_Manager. Each matching pair becomes a row in the join result.
Bank_Manager = Sunderajan: appears twice in the first subquery (Borrower = Ramesh, Mahesh) and twice in the second subquery (Loan_Amount = 10000.00, 7000.00), so 2 × 2 = 4 joined rows.
Bank_Manager = Ramgopal: appears once in each subquery (Suresh and 5000.00), so 1 × 1 = 1 joined row.
Total rows after the NATURAL JOIN = 4 + 1 = 5, so SELECT count(*) returns 5.
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