What uniquely identifies every record in a relational database?

A primary key uniquely identifies every record in a relational database. It is a specific attribute, or a combination of attributes, that ensures that each record can be distinguished from all other records in the same table. The primary key must contain unique values and cannot include null values, which reinforces the integrity of the database.

In relational database management systems, the concept of a primary key is crucial for establishing relationships between tables. For example, it allows for efficient data retrieval and supports referential integrity by linking to foreign keys in other tables, which reference the primary key and enhance the accuracy of data relationships.

The uniqueness enforced by a primary key helps maintain the integrity of the dataset by preventing duplicate records and ensuring that each entry can be reliably accessed through its primary key identifier. This is essential for the functionality of databases, as it allows users and systems to distinguish records easily.

While other terms like foreign key and index key have important roles within a database, they do not serve the primary function of uniquely identifying records within the same manner as a primary key. A record ID might also serve a similar purpose in certain contexts, but it is generally a less precise term as it can vary based on the specific implementation and may not always conform to the integrity constraints inherent in primary keys