1NF: atomic values, no repeating groups. 2NF: 1NF + no partial dependencies (all non-key attributes depend on full key). 3NF: 2NF + no transitive dependencies (non-key depends only on key). Example: Orders(order_id, customer_id, customer_name) violates 3NF—customer_name depends...
This easy-level SQL question appears frequently in data engineering interviews at companies like Kaseya. 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.
1NF: atomic values, no repeating groups. 2NF: 1NF + no partial dependencies (all non-key attributes depend on full key). 3NF: 2NF + no transitive dependencies (non-key depends only on key). Example: Orders(order_id, customer_id, customer_name) violates 3NF—customer_name depends on customer_id; split to Orders, Customers. BCNF: every determinant is candidate key. 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.
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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.