You should start a new thread for a new topic, however what you need here is
a conditional field.
{Mergefield LastName}{IF {Mergefield Suffix} <> "" ", {Mergefield Suffix}"}
should do the trick (change the field names to reflect your data).

Signature
<>>< ><<> ><<> <>>< ><<> <>>< <>><<>
Graham Mayor - Word MVP
My web site www.gmayor.com
Word MVP web site http://word.mvps.org
<>>< ><<> ><<> <>>< ><<> <>>< <>><<>
> how does one insert a comma that will print between the lastname and
> suffix fields in a mailmerge; eg John Jones, B.Sc.? I'm using Word
> and Excel for the database. all other functions are OK, including a
> coma between fields for city and state, eg Syracuse, New York. I
> can't get the comma to print between last name and suffix.