Showing selected item when editing form with select drop-down menu.

I've got a drop-down menu in a form that I created like this:

<%= select_tag 'employee[role]', options_for_select(
[['Admin','admin'],['Employee','employee']] ) %>

When editing a form, how do I get my drop-down to show the item from
the database as selected. Right now, it is just defaulting to the first
item in the drop-down list.

Thanks for the help.
Sarah