In database terminology, what is commonly used as a unique identifier for a set of records?

In database terminology, a key is indeed commonly used as a unique identifier for a set of records. A key serves to uniquely distinguish each record within a table, enabling efficient data retrieval and manipulation. For instance, primary keys are often defined for tables to ensure that no two records can have the same value in this column, effectively providing a unique identifier for each row.

Keys can take various forms, such as primary keys, foreign keys, and composite keys. This uniqueness is crucial in maintaining data integrity and establishing relationships between different tables (via foreign keys), which is essential in relational database management systems. The concept of a key enhances the relational model of databases by ensuring that each record can be identified and accessed accurately and consistently.

Other terms like ID or index may be related but do not capture the full scope of what a key signifies in the context of databases. An ID might be a straightforward attribute serving a similar purpose, but the term "key" encompasses more comprehensive functionalities, such as relational integrity and uniqueness within the database structure. An index serves to optimize the speed of data retrieval but does not necessarily ensure uniqueness, and a reference typically denotes a relationship between records rather than serving as a unique identifier.