**Architectural Logic**: SELECT dept_id, salary FROM (SELECT dept_id, salary, DENSE_RANK() OVER (PARTITION BY dept_id ORDER BY salary DESC) rk FROM employee) t WHERE rk = 2. DENSE_RANK ensures 'second' is the second distinct salary tier; RANK would skip if two people share...
This medium-level SQL question appears frequently in data engineering interviews at companies like Accenture, Yash Technologies. While less common, it tests deeper understanding that distinguishes strong candidates. Mastering the underlying concepts (partition, sql, window) 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.
Architectural Logic: SELECT dept_id, salary FROM (SELECT dept_id, salary, DENSE_RANK() OVER (PARTITION BY dept_id ORDER BY salary DESC) rk FROM employee) t WHERE rk = 2. DENSE_RANK ensures 'second' is the second distinct salary tier; RANK would skip if two people share first. Why: PARTITION BY dept_id gives per-department ranking. DENSE_RANK handles ties (e.g., two people at top salary → both rank 1, next is rank 2). Scalability: Single pass with sort per partition; narrow PARTITION BY helps. Cost: Standard window cost; dept_id filter before window reduces rows.
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According to DataEngPrep.tech, this is one of the most frequently asked SQL interview questions, reported at 2 companies. DataEngPrep.tech maintains a curated database of 1,863+ real data engineering interview questions across 7 categories, verified by industry professionals.