How to check free space in datafile & tablespace

--
-- Displays Space Usage for Each Datafile.
--

SET PAUSE ON
SET PAUSE 'Press Return to Continue'
SET PAGESIZE 60
SET LINESIZE 300
COLUMN "Tablespace Name" FORMAT A20
COLUMN "File Name" FORMAT A80

SELECT  Substr(df.tablespace_name,1,20) "Tablespace Name",
        Substr(df.file_name,1,80) "File Name",
        Round(df.bytes/1024/1024,0) "Size (M)",
        decode(e.used_bytes,NULL,0,Round(e.used_bytes/1024/1024,0)) "Used (M)",
        decode(f.free_bytes,NULL,0,Round(f.free_bytes/1024/1024,0)) "Free (M)",
        decode(e.used_bytes,NULL,0,Round((e.used_bytes/df.bytes)*100,0)) "% Used"
FROM    DBA_DATA_FILES DF,
       (SELECT file_id,
               sum(bytes) used_bytes
        FROM dba_extents
        GROUP by file_id) E,
       (SELECT Max(bytes) free_bytes,
               file_id
        FROM dba_free_space
        GROUP BY file_id) f
WHERE    e.file_id (+) = df.file_id
AND      df.file_id  = f.file_id (+)
ORDER BY df.tablespace_name,
         df.file_name
/

=======================================================================
set linesize 150
COLUMN file_name format A60
COLUMN free_space_mb format 999999.90
COLUMN allocated_mb format 999999.90
COLUMN used_mb format 999999.90

SELECT SUBSTR (df.NAME, 1, 60) file_name, df.bytes / 1024 / 1024 allocated_mb,
((df.bytes / 1024 / 1024) - NVL (SUM (dfs.bytes) / 1024 / 1024, 0))
used_mb,
NVL (SUM (dfs.bytes) / 1024 / 1024, 0) free_space_mb
FROM v$datafile df, dba_free_space dfs
WHERE df.file# = dfs.file_id(+)
GROUP BY dfs.file_id, df.NAME, df.file#, df.bytes
UNION ALL
select file_name, bytes/1024/1024 allocated_mb,user_bytes/1024/1024 used_mb,
((bytes/1024/1024) - (user_bytes/1024/1024)) free_space_mb
from dba_temp_files;
)
=======================================================================
SELECT SUBSTR (df.NAME, 1, 40) file_name,dfs.tablespace_name, df.bytes / 1024 / 1024 allocated_mb,
((df.bytes / 1024 / 1024) – NVL (SUM (dfs.bytes) / 1024 / 1024, 0))
used_mb,
NVL (SUM (dfs.bytes) / 1024 / 1024, 0) free_space_mb
FROM v$datafile df, dba_free_space dfs
WHERE df.file# = dfs.file_id(+)
GROUP BY dfs.file_id, df.NAME, df.file#, df.bytes,dfs.tablespace_name
ORDER BY file_name;
==============================datafile====================================
 SELECT B.TABLESPACE_NAME,
         B.FILE_NAME,
         ROUND (B.BYTES / 1024 / 1024 / 1024, 2) "SIZE GB",
         ROUND (B.MAXBYTES / 1024 / 1024 / 1024, 2) "MAX SIZE GB",
         ROUND (SUM (A.BYTES) / 1024 / 1024 / 1024, 2) "FREE SPACE GB",
         CASE
            WHEN MAXBYTES = 0
            THEN
               ROUND (SUM (A.BYTES) / 1024 / 1024 / 1024, 2)
            ELSE
               ROUND (
                    ( (B.MAXBYTES - B.BYTES) + SUM (A.BYTES)) / 1024 / 1024 / 1024, 2)
         END
            "TOTAL FREE SPACE GB"
    FROM DBA_FREE_SPACE A, DBA_DATA_FILES B
   WHERE A.FILE_ID = B.FILE_ID AND B.TABLESPACE_NAME IN ('CBAM')
GROUP BY B.TABLESPACE_NAME,
         B.FILE_NAME,
         B.BYTES,
         B.MAXBYTES
ORDER BY 1, 2;

==============================tablespace=================================
SELECT B.TABLESPACE_NAME,
         ROUND (SUM (B.BYTES) / 1024 / 1024 / 1024, 2) "SIZE GB",
         ROUND (SUM (B.MAXBYTES) / 1024 / 1024 / 1024, 2) "MAX SIZE GB",
         A.FREE_SPACE_GB "FREE SPACE GB",
         ROUND (
            (SUM (B.MAXBYTES - B.BYTES) / 1024 / 1024 / 1024) + A.FREE_SPACE_GB,
            2)
            "TOTAL FREE SPACE GB"
    FROM DBA_DATA_FILES B,
         (  SELECT TABLESPACE_NAME,
                   ROUND (SUM (BYTES) / 1024 / 1024 / 1024, 2) FREE_SPACE_GB
              FROM DBA_FREE_SPACE
             WHERE TABLESPACE_NAME IN ('CBAM')
          GROUP BY TABLESPACE_NAME) A
   WHERE     B.TABLESPACE_NAME IN ('CBAM')
         AND B.TABLESPACE_NAME = A.TABLESPACE_NAME
         AND B.MAXBYTES != 0
GROUP BY B.TABLESPACE_NAME, A.FREE_SPACE_GB
ORDER BY 1;