Self-join pairs employee with manager: SELECT e.employee_id, e.name, e.salary, m.salary AS manager_salary FROM employees e JOIN employees m ON e.manager_id = m.employee_id WHERE e.salary > m.salary. **Why self-join**: Hierarchical data in one table. **Edge case**: CEO has...
This medium-level SQL question appears frequently in data engineering interviews at companies like LTIMindtree. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (join) will help you answer variations of this question confidently.
Break this problem into components. Identify the core trade-offs involved, then walk the interviewer through your reasoning step by step. Demonstrate awareness of edge cases and production considerations - this is what separates good answers from great ones.
Self-join pairs employee with manager: SELECT e.employee_id, e.name, e.salary, m.salary AS manager_salary FROM employees e JOIN employees m ON e.manager_id = m.employee_id WHERE e.salary > m.salary. Why self-join: Hierarchical data in one table. Edge case: CEO has manager_id NULL—excluded by INNER JOIN. Use LEFT JOIN + WHERE manager_id IS NOT NULL if CEO shouldn't appear. Performance: Index on manager_id.
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Analyze My Answer — FreeAccording to DataEngPrep.tech, this is one of the most frequently asked SQL interview questions, reported at 1 company. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.