What is the primary purpose of a primary key in a database?

The primary purpose of a primary key in a database is to uniquely identify each record in a table. This unique identification ensures that no two records can have the same value in the primary key column(s), maintaining data integrity and facilitating the efficient retrieval of data. For example, in a table of students, a primary key could be a student ID, which would ensure that each student can be distinctly identified by that ID.

This unique identification is crucial for establishing relationships between different tables in a relational database. It allows other tables to reference records in the original table without ambiguity, thereby enhancing both data organization and the accuracy of queries.