SQL · Question 12 · Hard
SQL question 12
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
Table Projects has one column emp_id with rows: 1, 3, NULL
What does this query return?
SELECT COUNT(*)
FROM Employee
WHERE id NOT IN (SELECT emp_id FROM Projects);- 4
- 3
- 0
- 6
Answer and explanation
Answer: C. 0
Explanation: x NOT IN (1, 3, NULL) means x <> 1 AND x <> 3 AND x <> NULL. The comparison with NULL is UNKNOWN, so the condition is never TRUE and no rows qualify. The count is 0.
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