What is the purpose of using a primary key?

What is the purpose of using a primary key?

• A. To define all attributes equally
• B. To enforce referential integrity
• C. To uniquely identify each entity instance
• D. To allow for redundancy in data

Answer: (C)

The purpose of using a primary key is to uniquely identify each entity instance in a database. A primary key serves as a unique identifier for a record within a table, ensuring that no two records can have the same value for that key. This uniqueness is essential for distinguishing between different entities in a database, which allows for accurate referencing and retrieval of data. When a primary key is established, it also facilitates the management of relationships between tables. For example, it can be used in conjunction with foreign keys to create links across various tables, thereby supporting the relational model of databases. By ensuring each entity can be precisely identified, primary keys also lay the foundation for enforcing data integrity and consistency within the database. While other aspects, such as referential integrity, are indeed influenced by the use of primary keys, the primary function remains the unique identification of records. This leads to effective data management practices and prevents any ambiguity when interfacing with the database.

The purpose of using a primary key is to uniquely identify each entity instance in a database. A primary key serves as a unique identifier for a record within a table, ensuring that no two records can have the same value for that key. This uniqueness is essential for distinguishing between different entities in a database, which allows for accurate referencing and retrieval of data.

When a primary key is established, it also facilitates the management of relationships between tables. For example, it can be used in conjunction with foreign keys to create links across various tables, thereby supporting the relational model of databases. By ensuring each entity can be precisely identified, primary keys also lay the foundation for enforcing data integrity and consistency within the database.

While other aspects, such as referential integrity, are indeed influenced by the use of primary keys, the primary function remains the unique identification of records. This leads to effective data management practices and prevents any ambiguity when interfacing with the database.