Chapter 9 - Database Systems - Section 9.2 - The Relational Model - Questions & Exercises - Page 432: 6

Through common attributes. For instance, the $EMPLOYEE$ relation in this section is tied to the $ASSIGNMENT$ relation via the attribute $EmplId$, and the $ASSIGNMENT$ relation is tied to the $JOB$ relation by the attribute $JobId$. Attributes used to connect relations like this are sometimes called connection attributes.

Through common attributes. For instance, the $EMPLOYEE$ relation in this section is tied to the $ASSIGNMENT$ relation via the attribute $EmplId$, and the $ASSIGNMENT$ relation is tied to the $JOB$ relation by the attribute $JobId$. Attributes used to connect relations like this are sometimes called connection attributes.