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Normalization: 1NF, 2NF, 3NF with examples

SQLeasy0.4 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Kaseya
Expert AnswerPremium
80 wordsInterview-ready
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....
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