count returns <<air>> when there's nothing to group by - oracle

Question

Here's my SQL:
select
count(*)
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%FEE%'
group by
pwo;
When there's nothing to group by, count returns --air--. It's null nor is it blank. I have modified the above SQL as the following to prove.
select
'>>' || count(*) || '<<' as blah
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%ANNEAL%'
group by
pwo;
When I, however, write a statement above to perform an update, I got null. So tried coalesce, but got the same thing.
Does anyone know what I can do to replace --air-- with null or 0? Thanks!
P.S. I have did something research, but couldn't find anything...apologize in advance, if there's already a similar question out there.
Thanks!

Answer 1

This is what you currently have (based on Scott's EMP table): as there's no department 50, you get no rows selected (which is the air you're talking about, I presume).
SQL> with your_current_query as
2 (select count(*) cnt
3 from emp
4 where deptno = &deptno
5 group by job
6 )
7 select cnt
8 from your_current_query;
Enter value for deptno: 50
no rows selected
Just to show that it actually returns something if there are some data there:
SQL> /
Enter value for deptno: 30
CNT
----------
4
1
1
SQL>
OK; now, to do something with the situation where there are no rows selected, use union with a "dummy" row selected from the DUAL table:
SQL> with your_current_query as
2 (select count(*) cnt
3 from emp
4 where deptno = &deptno
5 group by job
6 )
7 select cnt
8 from your_current_query
9 -- add this: if YOUR_CURRENT_QUERY doesn't return anything, union it with
10 -- a select from dual
11 union all
12 select 0
13 from dual
14 where 0 = (select count(*) from your_current_query);
Enter value for deptno: 50
CNT
----------
0
SQL>
So: even though there are no employees in department 50, you got 0 as the result.
Again, to show what happens when there are some rows:
SQL> /
Enter value for deptno: 30
CNT
----------
4
1
1
SQL>
Finally, your query - rewritten - would look like this:
with your_current_query as
(select
count(*) cnt
from
sysdba.dw_cmap_arf_tmp
left join SYSDBA.TABLE1 rrc
on rrc.part_work_order = pwo
left join sysdba.TABLE2 R
on rrc.run_number = R.RUN_NUMBER
where
upper(run_type) like '%FEE%'
group by
pwo
)
select cnt from your_current_query
union all
select 0
from dual
where 0 = (select count(*) from your_Current_query);
See if it helps.