What is a primary key in a database?

A primary key in a database serves as a unique identifier for each record within a table, which is crucial for ensuring data integrity. This uniqueness means that no two records can have the same value for the primary key field, allowing for reliable identification and retrieval of records. In relational databases, primary keys are typically designated to prevent duplicate entries and maintain the relational integrity of the data.

By having a primary key, database management systems can efficiently and accurately enforce relationships between tables, preventing issues such as data redundancy and inconsistency. This unique nature of the primary key significantly benefits applications that interact with the database, as it allows for precise queries and updates, ensuring that operations identify the correct records without confusion.