SELECT category, product_id, product_name, sales FROM (SELECT category, product_id, product_name, sales, ROW_NUMBER() OVER (PARTITION BY category ORDER BY sales DESC) AS rn FROM products) ranked WHERE rn <= 3. **Why**: Define 'performing' (revenue, units, margin). Consider time...
This medium-level SQL question appears frequently in data engineering interviews at companies like Kagina. 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.
SELECT category, product_id, product_name, sales FROM (SELECT category, product_id, product_name, sales, ROW_NUMBER() OVER (PARTITION BY category ORDER BY sales DESC) AS rn FROM products) ranked WHERE rn <= 3. Why: Define 'performing' (revenue, units, margin). Consider time window (e.g., last 90 days). Scalability: Pre-aggregate in mart for dashboards. Use RANK/DENSE_RANK for ties.
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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.