Understanding Functional Dependencies

What is a functional dependency in DBMS?

• A functional dependency is a type of database normalization technique.

• A functional dependency is a relationship where one attribute can have multiple values for another attribute.

• A functional dependency is a relationship where one attribute uniquely determines another attribute in a database.

• A functional dependency is a method for indexing data in a database.

Define the term 'candidate key'.

• A candidate key is any attribute that can identify a record in a table.

• A candidate key is a set of attributes that may or may not uniquely identify a record.

• A candidate key is a primary key that is not used in the database.

• A candidate key is a minimal set of attributes that uniquely identifies a record in a table.

What is the difference between a primary key and a candidate key?

• A primary key is a selected candidate key that uniquely identifies records, while a candidate key is any potential key that can uniquely identify records.

• A primary key can be composed of multiple columns, while a candidate key cannot.

• A primary key is used for indexing, while a candidate key is used for data retrieval.

• A primary key is always a single column, while a candidate key can be multiple columns.

Explain the concept of normalization in databases.

• Normalization is the process of combining all data into a single table.

• Normalization eliminates the need for relationships between tables.

• Normalization is only concerned with data security and access control.

• Normalization in databases is the process of structuring data to minimize redundancy and dependency by dividing it into related tables.

What are the different normal forms in database normalization?

• 1NF, 2NF, 3NF, 4NF, 7NF

• 1NF, 2NF, 3NF, 6NF

• 1NF, 2NF, 3NF, BCNF, 4NF, 5NF

• 1NF, 2NF, 3NF, 4NF, 5NF, 6NF

What is the purpose of the First Normal Form (1NF)?

• To ensure that all values in a column are atomic and to eliminate repeating groups.

• To group similar data types together in a single column.

• To create relationships between different tables in a database.

• To ensure that all columns in a table are of the same data type.

How does the Second Normal Form (2NF) differ from the First Normal Form (1NF)?

• 2NF allows duplicate values, while 1NF does not.

• 1NF requires full functional dependency of non-key attributes.

• 2NF focuses on reducing data redundancy, while 1NF does not.

• 2NF requires full functional dependency of non-key attributes on the primary key, while 1NF requires atomicity of values.

What is a transitive dependency?

• A transitive dependency is a direct relationship between two primary keys.

• A transitive dependency occurs when a primary key depends on another primary key.

• A transitive dependency is when all attributes are dependent on the primary key directly.

• A transitive dependency is a functional dependency where a non-key attribute depends on another non-key attribute, which is indirectly dependent on the primary key.

Explain the Third Normal Form (3NF).

• A table is in Third Normal Form (3NF) if it is in Second Normal Form and all the attributes are functionally dependent only on the primary key.

• A table is in Third Normal Form if it contains no foreign keys.

• A table is in Third Normal Form if all attributes are dependent on each other.

• A table is in First Normal Form if it has no repeating groups.

What is Boyce-Codd Normal Form (BCNF)?

• A relation is in Boyce-Codd Normal Form (BCNF) if every determinant is a candidate key.

• A relation is in BCNF if it contains only one candidate key.

• A relation is in BCNF if every attribute is a primary key.

• A relation is in BCNF if it has no transitive dependencies.