SELECT F.TABLESPACE_NAME,
TO_CHAR ((T.TOTAL_SPACE - F.FREE_SPACE),'999,999') "USED (MB)",
TO_CHAR (F.FREE_SPACE, '999,999') "FREE (MB)",
TO_CHAR (T.TOTAL_SPACE, '999,999') "TOTAL (MB)",
TO_CHAR ((ROUND ((F.FREE_SPACE/T.TOTAL_SPACE)100)),'999')||' %' PER_FREE
FROM (
SELECT TABLESPACE_NAME,
ROUND (SUM (BLOCKS(SELECT VALUE/1024
FROM V$PARAMETER
WHERE NAME = 'GLOBAL_PAGE_SIZE')/1024)
) FREE_SPACE
FROM DBA_FREE_SPACE
GROUP BY TABLESPACE_NAME
) F,
(
SELECT TABLESPACE_NAME,
ROUND (SUM (BYTES/1048576)) TOTAL_SPACE
FROM DBA_DATA_FILES
GROUP BY TABLESPACE_NAME
) T
WHERE F.TABLESPACE_NAME = T.TABLESPACE_NAME
AND (ROUND ((F.FREE_SPACE/T.TOTAL_SPACE)*100)) < 80;