What do you call a primary or foreign key that is made up of multiple attributes?

A primary or foreign key composed of multiple attributes is referred to as a composite key. This term specifically denotes that the key consists of two or more columns that, when combined, uniquely identify a record in a table. Having multiple attributes in a composite key is crucial for maintaining the uniqueness of rows when a single attribute alone is insufficient to ensure uniqueness.

For example, in a database table for student enrollment, neither the student ID nor the course ID alone may uniquely identify a record. However, when combined, they form a complete identifier for a specific enrollment record, allowing the database to efficiently enforce relationships and maintain data integrity.

The other terms provided are not standard terminology used in database design. A compound key is often considered synonymous with composite key but is less commonly used in technical discussions. Combined key and multi-valued key are not recognized terms in this context. Multi-valued keys refer to a different concept in database design where a single attribute can hold multiple values, which is not relevant to the definition of keys that combine multiple attributes.