select a.tablespace_name,       totalspace,       nvl(freespace, 0) freespace,       (totalspace - nvl(freespace, 0)) used,       ((totalspace - nvl(freespace, 0)) / totalspace) * 100 "%USED"  from (select tablespace_name, sum(bytes) / 1048576 totalspace          from dba_data_files         group by tablespace_name) a,       (select tablespace_name, sum(Bytes) / 1048576 freespace          from dba_free_space         group by tablespace_name) b where a.tablespace_name = b.tablespace_name(+)   and ((totalspace - nvl(freespace, 0)) / totalspace) * 100 > 90--and nvl(freespace,0) < 1000  -- only list TSs < 1GB free order by 5 desc;