请达人看个代码问题所在

shiyiming

选出来和a0001所选的所有课程都相同的id（也就是a0003）
我写的代码既有a0003，又有a0004，请问问题出在哪里？谢谢

[code:2orabq8r]data aa;
        input id$5. course $ score;
        datalines;
a0001 physics 90
a0002 physics 10
a0002 stat 80
a0003 physics 60
a0001 math 70
a0003 math 30
a0004 physics 20
a0004 stat 80
a0004 math 90
;
run;
proc sql;
select id,count(id) as n
from aa
where course in (select course from aa where id='a0001')
group by id
having n=(select count(id) from aa where id='a0001') and id ne 'a0001';
quit;[/code:2orabq8r]

shiyiming

死猪头