inner query to return more than one row

Question

I am using oracle 11i in sql developer..

this is my query:

SELECT itm.stu_no,wm_concat(uif.names) 
FROM personal uif,Coll itm, Dep ihts
WHERE uif.stu_id IN('26',    '29',    '32')   
  and (uif.stu_no,uif.stu_no) in 
  (
       select itm.stu_no,itm.stu_test_no 
       from Col itm,Dep ihts  
       where itm.stu_no = ihts.stu_no
       AND itm.status = 'A'
       AND ihts.status = 'A'
  )
  AND itm.status = 'A'
  and  itm.stu_no=ihts.stu_no and ihts.status = 'A'
  group by itm.stu_no;

the inner query (marked as strong text ) returns...

stu_no             stu_test_no
-----------------------------------
123                 234

but the complete query is not returning any rows.

this is the expected result..

stu_no              wm_concat(names)
------------------------------------------
123                  James Alex
234                  (null)

Is there any way to get the expected result?

Answer 1

It doesn't work because you're asking uif.stu_no to be both 123 and 234 :
(123,123) is not in ((123,234))
and
(234,234) is not in ((123,234))

you can try this:

SELECT itm.stu_no,wm_concat(uif.names) 
FROM personal uif,Coll itm, Dep ihts
WHERE uif.stu_id IN('26',    '29',    '32')   
  and uif.stu_no in 
  (
       select itm.stu_no 
       from Col itm,Dep ihts  
       where itm.stu_no = ihts.stu_no
       AND itm.status = 'A'
       AND ihts.status = 'A'
       union all
       select itm.stu_test_no 
       from Col itm,Dep ihts  
       where itm.stu_no = ihts.stu_no
       AND itm.status = 'A'
       AND ihts.status = 'A'
  )
  AND itm.status = 'A'
  and  itm.stu_no=ihts.stu_no and ihts.status = 'A'
  group by itm.stu_no;

But why not:

SELECT itm.stu_no,wm_concat(uif.names) 
FROM personal uif, Coll itm, Dep ihts
WHERE uif.stu_id IN('26',    '29',    '32')   
  and (uif.stu_no = itm.stu_no OR uif.stu_no = itm.stu_test_no)
  AND itm.status = 'A'
  and itm.stu_no = ihts.stu_no 
  and ihts.status = 'A'
  group by itm.stu_no;