WITH numbered AS (SELECT num, ROW_NUMBER() OVER (ORDER BY id) rn, num - ROW_NUMBER() OVER (ORDER BY id) AS grp FROM logs) SELECT num FROM numbered GROUP BY num, grp HAVING COUNT(*) >= 3 LIMIT 1. **Why**: Consecutive same numbers share (num - rn); groups with COUNT >= 3 are...
This easy-level SQL question appears frequently in data engineering interviews at companies like JP Morgan. While less common, it tests deeper understanding that distinguishes strong candidates.
Start by clearly defining the core concept being asked about. Interviewers want to see that you understand the fundamentals before diving into implementation details. Structure your answer with a definition, then explain the practical application with a concise example.
WITH numbered AS (SELECT num, ROW_NUMBER() OVER (ORDER BY id) rn, num - ROW_NUMBER() OVER (ORDER BY id) AS grp FROM logs) SELECT num FROM numbered GROUP BY num, grp HAVING COUNT(*) >= 3 LIMIT 1. Why: Consecutive same numbers share (num - rn); groups with COUNT >= 3 are consecutive. Order by id for sequence. Classic: Gaps-and-islands pattern.
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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.