[SQL27] Query the ID of students who have studied both the '001' course and the '003' course

There is a score table SC, the table structure is SC (sid, cid, course), the branch corresponds to the student ID, course ID and student scores. The following test data

sid         cid             course
1           001             67
1           002             89
1           003             94
2           001             95
2           002             88
2           004             78
3           001             94
3           002             77
3           003             90

Query the ID of students who have studied both the '001' course and the '003' course. The expected result is
1
3

solve:

select a.sid
  from (
        select sid
              ,cid
          from sc a
         where cid = '001'
        ) a
  inner join (
              select sid
                    ,cid
                from sc a
               where cid = '003'
              ) b
     on a.sid = b.sid
;
sid
1
3

备注：建表和数据
create table sc(s_id int,c_id varchar(10),course int);
insert into sc values(1,'001',67);
insert into sc values(1,'002',89);
insert into sc values(1,'003',94);
insert into sc values(2,'001',95);
insert into sc values(2,'002',88);
insert into sc values(2,'004',78);
insert into sc values(3,'001',94);
insert into sc values(3,'002',77);
insert into sc values(3,'003',90);