select

   a.tablespace_name, to_char((sum(a.bytes)/1024/1024),’999999′),
          (select to_char((sum(b.bytes)/1024/1024),’999999′) from dba_data_files b where a.tablespace_name = b.tablespace_name)
from

dba_free_space a

group by a.tablespace_name

order by a.tablespace_name;