create table s (sid number, sname varchar(10));
create table e (sid number, cn number);
create table t (cn number, ctitle varchar(10));

insert into s(sid, sname) values (1001, 'Able');
insert into s(sid, sname) values (1002, 'Baker');
insert into s(sid, sname) values (1003, 'Cain');
select * from s;

insert into e(sid, cn) values (1002, 649);
insert into e(sid, cn) values (1003, 639);
insert into e(sid, cn) values (1002, 669);
select * from e;

insert into t(cn, ctitle) values (639, 'Marketing');
insert into t(cn, ctitle) values (649, 'Strategy');
insert into t(cn, ctitle) values (669, 'Technology');
select * from t;


select sname, ctitle from s, e, t where s.sid=e.sid and e.cn=t.cn;

select sname, ctitle from s, e, t where s.sid=e.sid and e.cn=t.cn order by ctitle;

select * from s, e, t where s.sid=e.sid and e.cn=t.cn order by ctitle;

select sname, ctitle from s, e, t where s.sid=e.sid and e.cn=t.cn and sname='Baker';

update s set sname='Delta' where sid=1002;

select * from s;

describe t;
select * from cat;

drop table person;

select * from cat;