db.txt

create table course (
    cid        integer not null,
    cname       varchar(40) not null,
    primary key (cid) );

insert into course values ('1', 'math');
insert into course values ('2', 'data structure');

create table student (
    sid        integer  AUTO_INCREMENT,
    sname       varchar(20) not null,
    primary key (sid) );
insert into student values (1000, 'Jones');
insert into student values (1001, 'jack');
insert into student values (1002, 'jason');
insert into student values (1003, 'tom');
insert into student values (1004, 'kevin');
insert into student values (1005, 'jerry');
insert into student values (1006, 'Zack');

    create table enrollment (
        sid        integer not null,
        cid        integer not null,
        primary key (sid, cid)
        );            // foreign key (sid) references student (sid)
insert into enrollment values (1000, 1);
insert into enrollment values (1002, 1);
insert into enrollment values (1003, 1);
insert into enrollment values (1004, 2);
insert into enrollment values (1001, 1);
insert into enrollment values (1005, 2);
insert into enrollment values (1006, 1);
insert into enrollment values (1006, 2);


////

select student.sid, student.sname, course.cname
from student, course, enrollment
where student.sid = enrollment.sid
and course.cid = enrollment.cid;