SELECT a.tablespace_name                           Tablespace,
       ROUND(( 1 - ( fbytes / tbytes ) ) * 100, 1) Percent_Used,
       ROUND(tbytes / 1024 / 1024, 1)              MB_Total,
       ROUND(fbytes / 1024 / 1024, 1)              MB_Free,
       ROUND(( tbytes - fbytes ) / 1024 / 1024, 1) MB_Used
FROM   (SELECT tablespace_name,
               SUM(bytes) tbytes
        FROM   dba_data_files
        GROUP  BY tablespace_name
        UNION ALL
        SELECT tablespace_name,
               SUM(bytes) tbytes
        FROM   dba_temp_files
        GROUP  BY tablespace_name) a
       LEFT OUTER JOIN (SELECT tablespace_name,
                               SUM(bytes) fbytes
                        FROM   dba_free_space
                        GROUP  BY tablespace_name
                        UNION ALL
                        SELECT tablespace_name,
                               SUM(user_bytes) fbytes
                        FROM   dba_temp_files
                        GROUP  BY tablespace_name) b
                    ON a.tablespace_name = b.tablespace_name