create table stu
(
sno int primary key,
sname varchar(12)
);

create table course
(
cno int primary key,
cname varchar(20)
);
create table report 
(
sno int references stu(sno),
cno int references course(cno),
grade int,
primary key(sno,cno)
);
insert into stu values(202101,'John');
insert into stu values(202102,'Mike');
insert into stu values(202103,'Tom');
insert into stu values(202104,'Smith');
insert into course values(1001,'English');
insert into course values(1002,'Maths');
insert into course values(1003,'Computer');
insert into course values(1004,'Game');
insert into report values(202101,'1001',60);
insert into report values(202102,'1001',70);
insert into report values(202102,'1002',80);
insert into report values(202102,'1003',90);
insert into report values(202103,'1001',90);
insert into report values(202103,'1002',50);
insert into report values(202104,'1004',55);
