ZoneID 17 is Blackburrow, not befallen, and the column you want to change is zone_id, not start_zone, but
Code:
UPDATE start_zones SET zone_id = '17' ;
worked for me, (created a new char and he started in Blackburrow) but like I say, the variables method I mentioned above is the accepted method of doing this, rather than messing with the start_zones table.