In the left pane of Sybase Central, double-click Tables.

In the left pane, click the SalesOrdersItems table to select it.

In the right pane, select the Constraints tab.

Choose File » New » Foreign Key.

In the To Which Table Do You Want This Foreign Key To Refer list, select the Products table.

In the What Do You Want To Name The New Foreign Key field, type ProductIDkey.

Click Next and for Do You Want This Foreign Key To Reference The Primary Key Or A Unique Constraint choose Primary Key.

In the Foreign Column list, click SalesOrdersItemsID.

Click Finish.