Group by function with CLOB fields in Select statement

Question

I have the following sql trying to query our database. Removing the Clob field (a.description) I am successful. But I need the Clob field (a.description). Here is my current sql
select  a.id_number, a.id_owner,  MAX (n.next_action_required)
            KEEP (DENSE_RANK LAST ORDER BY n.modified_date),
         MAX (n.modified_date) KEEP (DENSE_RANK LAST ORDER BY n.modified_date)
from table1 a, table2 n
where a.id_number = n.id_number
group by a.id_number, a.id_ownerI tried the following which works sometimes but not always because the Clob field (a.description)'s length varies; anywhere from 10 characters up to 12,000 characters. I get some blanks with the following and some where text is cut off. I may not be writing the dbms_lob.substr function correct.
select  a.id_number, a.id_owner,  MAX (n.next_action_required)
            KEEP (DENSE_RANK LAST ORDER BY n.modified_date),
         MAX (n.modified_date) KEEP (DENSE_RANK LAST ORDER BY n.modified_date) , DBMS_LOB.SUBSTR (a.description, 8001, 10000)
from table1 a, table2 n
where a.id_number = n.id_number
group by a.id_number, a.id_owner, DBMS_LOB.SUBSTR (a.description, 8001, 10000)Please help. Thank you,

Answer 1

Maybe,
but throw it away if the combination a.id_number,a.id_owner,n.next_action_required(a.id_number = n.id_number),n.modified_date(a.id_number = n.id_number) is not unique
select nd.id_number,
       nd.id_owner,
       nd.next_action_required,
       nd.modified_date,
       a.description
  from (select a.id_number,
               a.id_owner,
               MAX (n.next_action_required) KEEP (DENSE_RANK LAST ORDER BY n.modified_date) next_action_required,
               MAX (n.modified_date) KEEP (DENSE_RANK LAST ORDER BY n.modified_date) modified_date
          from table1 a,
               table2 n
         where a.id_number = n.id_number
         group by a.id_number,
                  a.id_owner
       ) nd,
       table1 a
where nd.id_number = a.id_number
   and nd.id_owner = a.id_owner
   and nd.id_number = (select id_number
                         from table2
                        where next_action_required = nd.next_action_required
                          and modified_date = nd.modified_date
                      )Regards
Etbin