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(Prog. Concept Question) DBMS relationship**
A relation is in X normal form if it is in Y normal form and there are no functional (transitive) dependencies between two (or more) non-primary key attributes. Choose correct X and Y.
Pick ONE option
Show answer & explanation
Third Normal Form (3NF) requires a relation to be in Second Normal Form (2NF) and have no transitive dependencies between non-primary key attributes. Transitive dependency means a non-key attribute depends on another non-key attribute rather than directly on the primary key. Option C correctly identifies this hierarchical relationship between normal forms.
Step-by-step Derivation:
Recall the definition of normal forms in database normalization:
- First Normal Form (1NF): No repeating groups; all attributes are atomic.
- Second Normal Form (2NF): Must be in 1NF AND have no partial dependencies (all non-key attributes depend on the entire primary key).
- Third Normal Form (3NF): Must be in 2NF AND have no transitive dependencies (no non-key attribute depends on another non-key attribute).
- Boyce-Codd Normal Form (BCNF): More restrictive than 3NF; every determinant must be a candidate key.
- Fourth Normal Form (4NF): Handles multivalued dependencies.
The definition given states: "X normal form if it is in Y normal form and there are no functional (transitive) dependencies between non-primary key attributes."
This directly describes 3NF, which requires being in 2NF plus the absence of transitive dependencies.
Evaluation of options:
- A) 2NF requires 1NF + no partial dependencies (not transitive), so this is incorrect.
- B) BCNF is built on 3NF, not 3NF on BCNF, and the requirement is different, so this is incorrect.
- C) 3NF requires 2NF + no transitive dependencies. ✓ Correct.
- D) 4NF handles multivalued dependencies, not transitive dependencies, so this is incorrect.