SQL Subquery Practice Sheet – 30+ Progressive Problems from Basics to MAANG-Level
Subqueries are among the most important—and most misunderstood—concepts in SQL.
This practice sheet is designed to help you build absolute clarity through structured, progressive problem-solving, not shortcuts or memorization.
You’ll work through 35 carefully designed SQL subquery problems, each grounded in realistic business scenarios with precise requirements and expected outputs.
What this practice sheet includes
Progressive difficulty breakdown:
- Easy (Problems 1–10): Scalar subqueries, IN / NOT IN, EXISTS, basic filtering
- Medium (Problems 11–20): Correlated subqueries, HAVING, ANY / ALL, nested patterns
- Medium-Advanced (Problems 21–30): Multiple EXISTS, running totals, relational division
- Advanced (Problems 31–35): FAANG-level interview problems with real business context
Learning approach
- Complete table setup (DDL & DML) for every problem
- Clearly defined business requirements
- Step-by-step solutions for Problems 1–30
- Advanced challenge problems intentionally left unsolved to test true understanding
This ensures you understand how subqueries work, where they fail, and how to reason through complex conditions with confidence.
Who this is for
- Beginners building a strong SQL foundation
- Intermediate learners struggling with correlated subqueries
- Advanced SQL users preparing for interviews
Recommended Roadmap
Step 1: Start with Easy and Medium problems (1–20)
Focus on understanding why a subquery is required, not just writing syntax.
Step 2: Move to Medium-Advanced problems (21–30)
Practice multiple subqueries, EXISTS logic, and relational division patterns.
Step 3: Attempt Advanced challenges (31–35)
Treat these as interview simulations. Solve independently before reviewing concepts.
How You’ll Practice
- Attempt each problem before checking the solution
- Rewrite queries using alternate subquery patterns where possible
- Trace correlated subqueries row by row
- Revisit difficult problems after a few days
- Focus on clarity, not query length
This method trains thinking, not guessing — exactly what SQL interviews demand.
:</strong> Scalar subqueries, IN / NOT IN, EXISTS, basic filtering</li><li><strong>Medium (Problems 11–20):</strong> Correlated subqueries, HAVING, ANY / ALL, nested patterns</li><li><strong>Medium-Advanced (Problems 21–30):</strong> Multiple EXISTS, running totals, relational division</li><li><strong>Advanced (Problems 31–35):</strong> FAANG-level interview problems with real business context</li></ul><p><br></p><h2><strong>Learning approach</strong></h2><ul><li>Complete table setup (DDL & DML) for every problem</li><li>Clearly defined business requirements</li><li>Step-by-step solutions for Problems 1–30</li><li>Advanced challenge problems intentionally left <strong>unsolved</strong> to test true understanding</li></ul><p>This ensures you understand <strong>how subqueries work, where they fail, and how to reason through complex conditions with confidence</strong>.</p><p><br></p><h2><strong>Who this is for</strong></h2><ul><li>Beginners building a strong SQL foundation</li><li>Intermediate learners struggling with correlated subqueries</li><li>Advanced SQL users preparing for interviews</li></ul><p><br></p><h2><strong>Recommended Roadmap</strong></h2><p><strong>Step 1:</strong> Start with Easy and Medium problems (1–20)</p><p>Focus on understanding <em>why</em> a subquery is required, not just writing syntax.</p><p><strong>Step 2:</strong> Move to Medium-Advanced problems (21–30)</p><p>Practice multiple subqueries, EXISTS logic, and relational division patterns.</p><p><strong>Step 3:</strong> Attempt Advanced challenges (31–35)</p><p>Treat these as interview simulations. Solve independently before reviewing concepts.</p><p><br></p><h2><strong>How You’ll Practice</strong></h2><ul><li>Attempt each problem before checking the solution</li><li>Rewrite queries using alternate subquery patterns where possible</li><li>Trace correlated subqueries row by row</li><li>Revisit difficult problems after a few days</li><li>Focus on clarity, not query length</li></ul><p><br></p><p><strong>This method trains thinking, not guessing — exactly what SQL interviews demand.</strong></p>&redirect_uri=http://www.facebook.com)
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