text: select df.tablespace_name "Tablespace",
  totalusedspace "Used MB",
  (df.totalspace - tu.totalusedspace) "Free MB",
  df.totalspace "Total MB",
  round(100 * ( (df.totalspace - tu.totalusedspace)/ df.totalspace))
  "Pct. Free"
  from
  (select tablespace_name,
  round(sum(bytes) / 1048576) TotalSpace
  from dba_data_files
  group by tablespace_name) df,
  (select round(sum(bytes)/(1024*1024)) totalusedspace, tablespace_name
  from dba_segments
  group by tablespace_name) tu
  where df.tablespace_name = tu.tablespace_name ;
  