BEGIN;
ALTER TABLE trunk ADD COLUMN route_on_to VARCHAR(3);
UPDATE trunk SET route_on_to = 'yes' WHERE route_on_to IS NULL;
ALTER TABLE trunk ALTER COLUMN route_on_to SET DEFAULT 'yes';
ALTER TABLE trunk ALTER COLUMN route_on_to SET NOT NULL;
ALTER TABLE trunk ADD CONSTRAINT trunk_route_on_to_check CHECK (route_on_to IN ('yes', 'no'));
COMMIT;
