Group By Substr in Derby

Derby doesn't let you do

select substr(some_column,1,10),count(*)
from some_table 
group by substr(some_column,1,10)

But you can get the same result by doing

select short_version,count(*) from
(
    select substr(some_column,1,10) as short_version 
    from some some_table
) a
group by short_version

Sam thought of this. The "a" is there as an alias name for the subselect. You don't have to use it, but if you don't put it in there, Derby rejects the SQL.