Database Management Concepts

What is a primary key in a database?

• A primary key is a type of foreign key.

• A primary key can be duplicated across records.

• A primary key is a unique identifier for a records.

• A primary key is used to store large amounts of data.

Define a foreign key and its purpose.

• Links two tables in a database, referencing the p.k of another table.

• A foreign key is a type of database index.

• A foreign key is a unique identifier for a table.

• A foreign key is a method for encrypting data in database management system.

What are the different types of keys in a relational database?

• Primary Key, Foreign Key, Unique Key, Candidate Key, Access Key

• Primary Key, Foreign Key, Unique Key, Composite Key, Candidate Key

• Primary Key, Foreign Key, Unique Key, Composite Key, Index Key

• Primary Key, Foreign Key, Unique Key, Composite Key, Data Key

Explain the concept of normalization in databases.

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

• Normalization process of organizing data to reduce redundancy.

• Normalization increases data redundancy for better performance.

• Normalization is a method to encrypt sensitive data in databases.

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

• Columns contain atomic values and eliminate repeating groups.

• To ensure all data is stored in a single column.

• To allow for duplicate entries in a table.

• To group related data into separate tables.

Describe the Second Normal Form (2NF) and its requirements.

• Second Normal Form (2NF) if it is in First Normal Form (1NF) and all non-key attributes are fully functionally dependent.

• A table is in Second Normal Form (2NF) if it has a single primary key without any non-key attributes.

• A table is in Second Normal Form (2NF) if it contains duplicate rows.

• A table is in Third Normal Form (3NF) if it has no transitive dependencies.

What is the Third Normal Form (3NF) and why is it important?

• Third Normal Form (3NF) allows for duplicate data entries.

• 3NF is a method for data encryption in databases.

• Third Normal Form (3NF) is used to increase data redundancy.

• Third Normal Form (3NF) is a database normalization form that eliminates transitive dependencies.

What is a functional dependency in the context of databases?

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

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

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

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

How do you determine a minimal cover for a set of functional dependencies?

• A minimal cover includes all attributes from the original set.

• A minimal cover is a set of functional dependencies that has more dependencies than the original set.

• A minimal cover is a set of functional dependencies that is equivalent to the original set but has no extraneous attributes or redundant dependencies.

• A minimal cover is a set of functional dependencies that can be derived from the original set without any changes.

What is an aggregation function in SQL?

• A function that retrieves data from a database

• Function that computes a single result from a set of input values.

• A method to update existing data in a database

• A command to delete records from a table