You work as the database administrator at Domain.com. All servers on the Domain.com network run Windows Server 2003 and all database servers run SQL Server 2005. The Domain.com network contains a database server named Certkiller -DB01 B01. Certkiller -DB01 hosts a database named CK_Sales that stores sales data for the company. The tables in the CK_Sales database are shown in the following database diagram.

Domain.com decides to switch to commission-based salaries for its Sales staff. The manager of the Sales department will run queries against the Invoices table to calculate the commission for each sales person. To ensure the success of the queries, you want to enforce the values that the SalesPersonID column in the Invoices table will accept.
exhibit What should you do?