WITH consec AS (SELECT num, id, num - ROW_NUMBER() OVER (ORDER BY id) AS grp FROM t) SELECT num FROM consec GROUP BY num, grp HAVING COUNT(*) >= 3 ORDER BY MIN(id) LIMIT 1. **Why**: Consecutive same nums share (num - rn); first group with 3+ = first occurrence....
This easy-level SQL question appears frequently in data engineering interviews at companies like American Express. 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 consec AS (SELECT num, id, num - ROW_NUMBER() OVER (ORDER BY id) AS grp FROM t) SELECT num FROM consec GROUP BY num, grp HAVING COUNT(*) >= 3 ORDER BY MIN(id) LIMIT 1. Why: Consecutive same nums share (num - rn); first group with 3+ = first occurrence. Classic: Gaps-and-islands.
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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.