Question

I have a how do I do this in Oracle?

select a.field1 || '_' || 
       b.field2 || '_' || 
       sum(c.field3)
  from table1 a, 
       table2 b, 
       table3 c
 where a.field1 || '_' || 
       b.field2 || '_' || 
       sum(c.field3) not in (select d.field1 || '_' || 
                                    e.field2 || '_' || 
                                    sum(f.field3)  
                               from table4 d, 
                                    table5 e, 
                                    table6 f
                              where conditional_info_to_join_the_tables 
                              group by d.field1, e.field2)
   and conditional_info_to_join_the_tables  
 group by a.field1, b.field2

The error I get is I can’t use the sum in the where clause

i have tried using

select a.field1 || '_' || 
       b.field2 || '_' || 
       sum(c.field3), 
       sum(c.field2) foo
  from table1 a, 
       table2 b, 
       table3 c
 where a.field1 || '_' || 
       b.field2 || '_' || 
       foo not in (select d.field1 || '_' || 
                          e.field2 || '_' || 
                          sum(f.field3)  
                     from table4 d, 
                          table5 e, 
                          table6 f
                    where conditional_info_to_join_the_tables 
                    group by d.field1, e.field2)
   and conditional_info_to_join_the_tables 
 group by a.field1, b.field2

but that foo was not an identified variable.

Answer 1

Merely giving the sum and alias (foo) does not help because the aggregate occurs after the filtering (the where clause.

The having clause is like a filter that applies after the aggregation:

select a.field1 || '_' || b.field2 || '_' || sum(c.field3)
from table1 a, table2 b, table3 c
where conditional_info_to_join_the_tables
group by a.field1, b.field2
having a.field1 || '_' || b.field2 || '_' || sum(c.field3)
           not in ( select d.field1 || '_' || e.field2 || '_' || sum(f.field3) 
                    from table4 d, table5 e, table6 f
                    where conditional_info_to_join_the_tables 
                    group by d.field1, e.field2 )

You will still need to write out the aggregate in full rather than aliasing—the reason behind this is a bit less obvious and is discussed in this answer over on dba.se: https://dba.stackexchange.com/a/21982/1396.

Of course you can achieve the same with a subquery:

select foo
from( select a.field1 || '_' || b.field2 || '_' || sum(c.field3) as foo
      from table1 a, table2 b, table3 c
      where conditional_info_to_join_the_tables
      group by a.field1, b.field2 )
where foo not in ( select d.field1 || '_' || e.field2 || '_' || sum(f.field3) 
                   from table4 d, table5 e, table6 f
                   where conditional_info_to_join_the_tables 
                   group by d.field1, e.field2 )