insert into student values(1,'A');
insert into student values(2,'B');


insert into phone_hot values(1,'0000003');
insert into phone values(1,'0000003');

start transaction;
insert into phone_hot values(1,'0000004');
insert into phone values(1,'0000004');
commit;

insert into phone values(1,'0000005');

update phone_hot set id='0000005' where s_id=1;

delete from phone where id='0000004';

delete from phone where id='0000005';
delete from phone_hot where s_id=1;

start transaction;
delete from phone where id='0000005';
delete from phone_hot where s_id=1;
commit;