In FileMaker, you can make two databases work together as easily as you work with multiple tables. Using the data tunneling techniques discussed in the previous section, you connect tables from another file (often called an external database) without the overhead of copying all that data into your file. You simply put a table occurrence from your external file onto your relationship graph, which defines its perspective in relation to all your other tables.
For example, suppose you want to connect the People database you created in Chapter 3 to your new system. You'd like a portal on the Customers layout to show all the people in the People database who live in the same state as that customer. After all, you never know when one of your leads will come in handy.