Print mailing labels and update date field

Sorry if this shows up twice, I clicked on post but could not find the
post....!

I have a database which requires the batch import of customer contact
information, print mailing labels for those customers whose date of
first letter field is null, and update the date of first letter field
when the mailing labels are printed,

I already have a query which checks the date of first letter field and
returns the customer contact information if the date of first letter
field is null. Based on this query criteria how can I print mailing
labels and update the date of first letter field at the same time?

Thanks