problem in select query

[tamilselvan]

Thanks akkerend. You did excellent job.

Slimdave, You missed some thing.

10:39:15 SQL> L
1 select student_id
2 from my_table
3 where course in ('java','c')
4 group by student_id
5* having count(distinct course) = 2
10:39:18 SQL> /

STUDENT_ID
----------
13
15

Once again Big Thanks to akkerend.

Another method:

select student_id
from
(
select student_id ,
       sum(case
        when course = 'c' then 1
         else 0
       end) c_count,
       sum(case
        when course = 'java' then 1
         else 0
       end) java_count,
       sum(case
        when course <> 'java' and course <> 'c' then 1
         else 0
       end) oth_count
from my_table
group by student_id
)
where c_count =1 and java_count=1 and oth_count = 0
/
~ 

Tamil