Understanding Functional Dependencies

What is a functional dependency?

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

• A functional dependency is a type of database index.

• A functional dependency is a relationship where one attribute's value determines another's value in a database.

• A functional dependency is a way to encrypt data in a database.

Define the term 'attribute' in the context of databases.

• An attribute is a property or characteristic of an entity in a database, typically represented as a column in a table.

• An attribute is a command used to manipulate data in a database.

• An attribute refers to the entire database structure.

• An attribute is a type of database that stores multiple entities.

What does it mean for a relation to be in 1NF?

• A relation is in 1NF if it contains nested values.

• A relation is in 1NF if it allows duplicate records.

• A relation is in 1NF if it contains only atomic values and each record is unique.

• A relation is in 1NF if it has no primary key.

Explain the concept of a candidate key.

• A candidate key is a foreign key that links two tables.

• A candidate key is a unique identifier for a record in a database table, consisting of one or more attributes.

• A candidate key can have duplicate values in a database table.

• A candidate key is an optional attribute that may or may not be present in a record.

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

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

• Both primary key and candidate key are the same and can be used interchangeably.

• A primary key can have duplicate values, while a candidate key cannot.

• A candidate key is always chosen as the primary key in a database.

Describe the process of normalization.

• Normalization involves creating multiple copies of the same data for backup purposes.

• Normalization is the process of deleting all data from a database.

• Normalization is the method of encrypting data to enhance security.

• Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

What is the purpose of functional dependencies in database design?

• To simplify the user interface of the database.

• To define relationships between attributes and ensure data integrity in database design.

• To eliminate redundancy in all database designs.

• To increase the number of attributes in a database.

How do you determine if a set of attributes is a superkey?

• A set of attributes is a superkey if it can uniquely identify all tuples in a relation.

• A superkey must consist of only one attribute.

• A superkey is defined by its ability to group tuples together.

• A set of attributes is a superkey if it can identify some tuples in a relation.

What is the significance of the closure of a set of attributes?

• The closure of a set of attributes is irrelevant to database design.

• The closure of a set of attributes determines the physical storage of data.

• The closure of a set of attributes is used to create user interfaces.

• The closure of a set of attributes helps identify all attributes that can be functionally determined, aiding in database normalization and dependency analysis.

Explain the concept of transitive dependency.

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

• A transitive dependency is when all attributes are dependent on each other without any keys involved.

• Transitive dependency refers to a direct relationship between two primary keys.

• A transitive dependency occurs when a primary key is dependent on a non-key attribute.