1. What is the purpose of a subquery in Oracle?

2. Which keyword is used to compare a single value with the result of a subquery in a WHERE clause?

3. In a correlated subquery, what is unique compared to a regular subquery?

4. Which operator is used to check if a subquery returns any rows?

5. What type of subquery returns a list of values for the main query to use with the IN keyword?

6. In a subquery, which clause is used to specify the conditions that determine the rows returned by the subquery?

7. What is the result of a subquery that returns no rows?

8. Which type of subquery is independent of the outer query and can be executed on its own?

9. Which keyword is used to negate the result of a subquery in a WHERE clause?

10. What does a subquery enclosed in parentheses () return?

11. Which SQL clause is used to filter the result set of a subquery?

12. What is the purpose of a nested subquery?

13. Which type of subquery is used to compare a value to a set of values returned by the subquery?

14. In a correlated subquery, what does the inner query depend on for its result set?

15. What happens if a subquery returns multiple rows and is used with the = operator in the main query’s WHERE clause?

16. Which operator is used to compare a value to a list of values returned by a subquery in the WHERE clause?

17. In a correlated subquery, what is the relationship between the inner and outer queries?

18. What is the result of a subquery that returns multiple rows and is used with the = operator in the main query’s WHERE clause?

19. What does the EXISTS keyword check for in a subquery?

20. Which type of subquery is executed once for each row processed by the outer query?

21. In a correlated subquery, how are the inner and outer queries related?

22. What is the primary use of a subquery in a SELECT statement?

23. Which SQL keyword is used to exclude rows that meet a condition in a subquery?

24. What does a nested subquery allow you to do that a scalar subquery does not?