SQl

create table students(st_id int,st_name varchar(20),st_ph int(30));
alter table students add(st_addrs varchar(30));
insert into students values('01','aaa','123','pol');
insert into students values('02','bbb','345','cov');
insert into students values('03','ccc','678','chen');
select * from students;
select st_ph from students;
select st_id from students;
update students set st_name='ddd' where st_id='01';
select * from students;
update students set st_ph='999' where st_id='01';
select * from students;