Database: activity_1
Question: Find the first names of professors who are not playing Canoeing.
SQL: select lname from faculty where rank  =  "professor" except select distinct t1.lname from faculty as t1 join faculty_participates_in as t2 on t1.facid  =  t2.facid join activity as t3 on t2.actid  =  t2.actid where t3.activity_name  =  "canoeing"