In database design, a compound key (also called a composite key or concatenated key) is a key that consists of 2 or more attributes.

No restriction is applied to the attributes regarding their (initial) ownership within the data model. This means that any one, none, or all, of the multiple attributes within the compound key can be foreign keys. Indeed, a foreign key may, itself, be a compound key.

Compound keys almost always originate from attributive or associative entities (tables) within the model, but this is not an absolute.

See also

• relational database
• compound key
• candidate key
• primary key
• alternate key
• foreign key
• unique key

Data modeling | Составной ключ

External Links

• Composite Inverse Functional Properties: for an equivalent notion in the Semantic Web