Free SQL Advanced Level Practice quiz
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Master complex database concepts with the Free SQL Advanced Level Practice Quiz on Quizsm. This practice zone is designed for learners and professionals who want to challenge their SQL expertise through advanced, real-world-oriented quizzes—completely free of cost.
The quizzes cover advanced SQL topics such as complex joins, nested and correlated subqueries, window functions, indexing strategies, query optimization, performance tuning, views, stored procedures, and transaction management. With a mix of multiple-choice and true/false questions, this practice zone evaluates both deep conceptual understanding and practical problem-solving skills.
With unlimited free access, you can attempt quizzes multiple times, identify critical knowledge gaps, and refine your expertise through continuous self-assessment. This helps you build confidence in handling complex database queries and prepares you for high-level technical interviews and real-world data challenges.
The Free SQL Advanced Practice Quiz is ideal for experienced learners aiming to strengthen their database skills and achieve mastery in SQL. Start practicing today and elevate your SQL proficiency with Quizsm.
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Question 1 of 5
1. Question
A table sales contains columns (id, sale_date, amount). Consider the query:
SELECT sale_date, amount, SUM(amount) OVER (ORDER BY sale_date) AS running_total FROM sales;Two rows share the same sale_date. Which behavior is correct in most SQL engines when using the default window frame?
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Question 2 of 5
2. Question
Suppose a table orders has 10 million rows and customers has 1 million rows. Consider two queries:
Query A:SELECT * FROM customers c WHERE EXISTS ( SELECT 1 FROM orders o WHERE o.customer_id = c.id );Query B:
SELECT * FROM customers WHERE id IN (SELECT customer_id FROM orders);Which statement is most accurate for modern cost-based optimizers?
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Question 3 of 5
3. Question
Consider a recursive CTE used to traverse an employee hierarchy:
WITH RECURSIVE emp_tree AS ( SELECT id, manager_id FROM employees WHERE manager_id IS NULL UNION ALL SELECT e.id, e.manager_id FROM employees e JOIN emp_tree t ON e.manager_id = t.id ) SELECT * FROM emp_tree;If the table contains a circular relationship (Employee A manages B, and B manages A), what is the most likely result in engines without cycle detection?
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Question 4 of 5
4. Question
Transaction T1 executes:
BEGIN; SELECT COUNT(*) FROM orders WHERE status='PENDING';Before T1 commits, Transaction T2 inserts a new PENDING order and commits.
If T1 repeats the same SELECT and still sees the original count, which isolation level is most likely being used?
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Question 5 of 5
5. Question
A table has the following composite index:
INDEX idx_user_activity (user_id, activity_date)Which query can fully use the index for filtering?
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