Functional Dependency and Normalization

What is a functional dependency in the context of relational databases?

• It describes the relationship between two tables

• It describes the relationship between two or more attributes within a table

• It describes the relationship between primary and foreign keys

• It describes the relationship between two databases

In a functional dependency A → B, what does A represent?

• Primary Key

• Determinant

• Foreign Key

• Attribute

Which of the following statements is true about functional dependencies?

• A functional dependency always holds true for every instance of a relation

• A functional dependency may not hold true for every instance of a relation

• Functional dependencies are only applicable to primary keys

• Functional dependencies are static and cannot change

In a functional dependency A → B, if two tuples have the same value for A, what can you infer about their values for B?

• They must have different values for B

• They must have the same value for B

• There's no constraint on their values for B

• B must be a composite attribute

What is a superkey in the context of functional dependencies?

• A key that uniquely identifies each tuple in a relation

• A key that is a subset of another key

• A key that cannot be determined by any other attribute

• A key that uniquely identifies a functional dependency

What is the purpose of normalization with respect to functional dependencies?

• To optimize database storage

• To eliminate redundancy and anomalies

• To speed up query execution

• To enforce referential integrity

What is the difference between a candidate key and a primary key in the context of functional dependencies?

• A candidate key can have multiple values, while a primary key must have a unique value

• A candidate key uniquely identifies each tuple, while a primary key is chosen from the candidate keys

• A candidate key can be composed of multiple attributes, while a primary key must be a single attribute

In a relation R(A, B, C, D), if A → B and B → C, what can be inferred about the functional dependency A → C?

• A → C holds

• A → C does not hold

• A → C is a trivial dependency

• A → C is transitive

When is a relation considered to be in Second Normal Form (2NF)?

• When it contains no partial dependencies

• When it contains only trivial functional dependencies

• When it contains only composite keys

• When it contains no transitive dependencies

What is a partial dependency in the context of functional dependencies?

• When one attribute functionally determines another attribute

• When a composite key determines a non-key attribute

• When an attribute is functionally determined by part of a composite key

• When an attribute cannot be determined by any other attribute