1.Create Table
create table Course (stu_id varchar2(20) not null, stu_name varchar2(20) not null, stu_course varchar2(20) not null, stu_score varchar2(10) not null )
2.Add column
alter table Course add check_time Date default sysdate;
3.Modify column
alter table Course modify(field_name varchar2(20) defaults 'unknown')
4.rename column
alter table Course rename column field_name to new_field_name
5.delete column
alter table Course drop column col_name
6.grant
grant select on Course to public