What is a primary key used for in a database table?

A primary key is essential in a database table as it serves the crucial function of uniquely identifying each record. This uniqueness ensures that no two records share the same value in the primary key field, which is fundamental for maintaining data integrity. By having a primary key, databases can efficiently retrieve, update, and manage records, as the system can easily distinguish one record from another based purely on this unique identifier.

Additionally, the use of a primary key allows for the establishment of relationships between different tables within a database. For instance, a primary key in one table can be referenced by foreign keys in other tables, creating connections between related data entries across the database. This structure leverages the relational nature of databases to organize and manipulate data more effectively.

While sorting records, encrypting sensitive information, and linking to external data are important functionalities within database operations, they are not the main purpose of a primary key. The defining characteristic of a primary key is its role in ensuring that each record can be uniquely accessed and identified.