drop table stu;
drop table class;
create table class(
id number(4) primary key
);
insert into class (id) values (1000);
create table stu(
id number(6),
name varchar2(20) constraint stu_name_nn not null,
sex number(1),
age number(3),
sdate date,
grade number(2) default 1,
class number(4),
email varchar2(50),
constraint stu_class_fk foreign key (class) references class(id),
constraint stu_id_pk primary key (id),
constraint stu_name_email_nui unique(email,name)
);
select * from class;
select * from stu;