Composite Key in RDBMS

A primary key having two or more attributes is called composite key. It is a combination of two or more columns.

An example can be −

Here our composite key is OrderID and ProductID −

Let us see another example −

<Student>

Above, our composite keys are StudentID and StudentEnrollNo. The table has two attributes as primary key.

Therefore, the Primary Key consisting of two or more attribute is called Composite Key.