Reviewed by Aditya Kumar · Last reviewed 2026-03-24
2nd latest joining per department: WITH ranked AS (SELECT *, DENSE_RANK() OVER (PARTITION BY dept ORDER BY join_date DESC) rn FROM employees) SELECT * FROM ranked WHERE rn=2. Use DENSE_RANK so ties get same rank; ROW_NUMBER gives unique rank. Alternative: NTH_VALUE or LAG. **Why...
2nd latest joining per department: WITH ranked AS (SELECT , DENSE_RANK() OVER (PARTITION BY dept ORDER BY join_date DESC) rn FROM employees) SELECT FROM ranked WHERE rn=2. Use DENSE_RANK so ties get same rank; ROW_NUMBER gives unique rank. Alternative: NTH_VALUE or LAG. Why it matters: Design choices compound at scale—wrong approach can cause 100× overhead. Scalability trade-offs: Profile before optimizing; validate on sample then full. Cost implications: Suboptimal choices multiply at billion-row scale.
Red Flag: Generic textbook answers. Pro-Move: 'At scale we measured X, implemented Y, achieved Z%—validated and iterated.'
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