SQL · Question 13 · Hard
SQL question 13
Table Employee:
id | name | dept | salary
1 | Asha | HR | 30000
2 | Ravi | IT | 50000
3 | Neha | IT | 60000
4 | Karan | Sales | NULL
5 | Priya | HR | 45000
6 | Vikram | IT | 50000
What does this query return?
SELECT COUNT(*)
FROM Employee e1
JOIN Employee e2
ON e1.salary = e2.salary AND e1.id < e2.id;- 2
- 6
- 0
- 1
Answer and explanation
Answer: D. 1
Explanation: Only Ravi (id 2) and Vikram (id 6) share a salary (50000). The condition e1.id < e2.id keeps just the pair (2, 6), so the count is 1. NULL = NULL is not TRUE, so Karan never matches.
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