Several tables in the iqdemo database refer to other tables in the database. For example, in the SalesOrders table, the SalesRepresentative column indicates which employee is responsible for an order. Only enough information to uniquely identify an employee is kept in the SalesOrders table. The SalesRepresentative column in the SalesOrders table is a foreign key to the Employees table.
A foreign key is one or more columns that contain candidate key values from another table. (For more about candidate keys, see Chapter 5, “Working with Database Objects,” in the System Administration Guide: Volume 1.)
