BEGIN;
alter table phoneline add column ringmobile varchar(3);
update phoneline set ringmobile = 'no' where ringmobile is NULL;
alter table phoneline alter column ringmobile set default 'no';
alter table phoneline alter column ringmobile set NOT NULL;
alter table phoneline add constraint phoneline_ringmobile_check CHECK (ringmobile IN ('yes', 'no'));
COMMIT;

