[Zope] submitting multi-checkbox

I'm trying to submit multi-checkbox (Formulator widget) values to a database using ZSQL. My database schema defines the fields as boolean; Formulator converts the values to a list of checked items, e.g. ['checked_item_one', 'checked_item_two']. Only checked items are added to the list. How can I map the formulator output to proper SQL? (a list of booleans) I have a couple of ideas, but I'm new to Zope and not sure what would be best, or even possible. Thanks Norman Lorrain