SQL - Database Design and Normalization
Why does Third Normal Form (3NF) require that non-key attributes depend only on the primary key and not on other non-key attributes?
Why does Third Normal Form (3NF) require that non-key attributes depend only on the primary key and not on other non-key attributes?
hard📝 Conceptual Q10 of 15
Step-by-Step Solution
Solution:
Step 1: Understand transitive dependencies
When non-key attributes depend on other non-key attributes, changes can cause inconsistent data.Step 2: Purpose of 3NF
3NF removes these transitive dependencies to avoid update, insert, and delete anomalies.Final Answer:
To prevent update anomalies caused by transitive dependencies -> Option BQuick Check:
3NF avoids update anomalies by removing transitive dependencies [OK]
Quick Trick: 3NF stops update problems by removing indirect dependencies [OK]
Common Mistakes:
- Thinking 3NF allows multiple primary keys
- Confusing indexing with normalization
- Believing 3NF reduces table count
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