Infopath - Populate a text box depending on the selection of a dropdown list

Hi there,
couldn't find an Infopath section hopefully this section is close enough :)

I've just created a form to test this out to see if it can be done - I've created the form based on a connection to a database. The database contains 2 fields - FullName & EmailAddress.
The form contains two controls -
A drop down list - linked to the FullName Field
A text box - this I want to update depending on the selection in the drop down list.

If Employee 1 is selected from the drop down I want that employees email address to populate the text box.

Can this be done?

Many thanks in advance

Michael