Subqueris in Casestatement

Question

Hi,
I'm trying to use the subquery in case statement in 11g it is working fine. But its throwing the ORA-00979: not a GROUP BY expression in 10g. Will 10g wont support subqueries in case statement ?
Appreciated your help.
select month,
       case when  workflow_type in (select document_type from document_type_filters where filters='initial') then 'cawv_initial_ca'
            when  workflow_type in (select document_type from document_type_filters where filters='annual') then 'cawv_annual_ca'          
       end kri,count(workflow_id) itms_total
from  me_data
where month='30-sep-11'
      and (workflow_type in (select document_type from document_type_filters where filters in ('annual','initial')
group by nvl(completed_by, 'unknown'),
         case when  workflow_type in (select document_type from document_type_filters where filters='initial') then 'cawv_initial_ca'
              when  workflow_type in (select document_type from document_type_filters where filters='annual') then 'cawv_annual_ca'         
         end; Regards,
Venkat

Answer 1

Hi, Venkat,
month is not in the GROUP BY clause.
I don't have an Oracle 11 database right now. I couldn't test it anyway, because I don't have those tables.
whenever you have a problem, post CREATE TABLE and INSERT statements for a little sample data, or else use commonly available tables (such as those in the scott or hr schemas) to show your problem.
Your code will be easier to debug and maintain i9and probably more efficient) if you compute kri once, in a sub-query, so that the CASE espression doesn't have to be repeated.
It will also be more efficient if you only do one sub-query using document_type_filters, like this:
WITH     got_kri          AS
     SELECT     month
     ,     CASE  (
               SELECT  MIN ( CASE  document_type_filters
                                   WHEN  'initial'     THEN  1
                             WHEN  'annual'     THEN  2
                          END
               FROM     document_type_filters
               WHERE     document_type          = m.workflow_type
               AND     document_type_filters     IN ('annual', 'initial')
                WHEN  1     THEN  'cawv_initial_ca'
                WHEN  2     THEN  'cawv_annual_ca'
          END     AS kri
     ,     workflow_id
     FROM     me_data
     WHERE     month     = '30-sep-11'     -- Use DATEs when appropriate
SELECT       month
,       kri
,       COUNT (workflow_id)     AS itms_total
FROM       got_kri
GROUP BY  month
,            kri
;Depending on you data, it could be simpler and more efficient still to join me_data and document_type_filters, rather than use a sub-query.
Edited by: Frank Kulash on Nov 7, 2011 6:26 AM
Added alternative query