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

The primary purpose of having a primary key in a database table is to uniquely identify each record in that table. This unique identification ensures that no two records can have the same primary key value, allowing for precise data retrieval, management, and integrity. For example, in a table of customers, the primary key might be a customer ID that ensures each customer's information can be accessed without confusion with other customers. This unique identifier helps to maintain order within the database and is crucial for establishing relationships between different tables in the database, such as linking customers to their orders while preventing any ambiguity.

In contrast, allowing duplicate entries would undermine the purpose of a primary key, since a key must be unique. Connecting multiple tables without restrictions does not align with the role of a primary key, as relationships often depend on unique keys to maintain integrity. Enhancing graphical user interfaces is unrelated to the concept of a primary key, as it deals more with the presentation layer of applications rather than the data structure and integrity enforced by keys in a database.