SELECT A.TABLESPACE_NAME
, ROUND(A.TOTAL_MB, 2) AS TOTAL_MB
, ROUND(B.FREE_MB, 2) AS FREE_MB
, ROUND(A.TOTAL_MB - B.FREE_MB, 2) AS USED_MB
, ROUND((B.FREE_MB / A.TOTAL_MB) * 100, 2) AS FREE_PCT
FROM (
SELECT TABLESPACE_NAME
, SUM(BYTES)/1024/1024 AS TOTAL_MB
FROM DBA_DATA_FILES
WHERE TABLESPACE_NAME = 'SYSAUX'
GROUP BY TABLESPACE_NAME
) A,
(
SELECT TABLESPACE_NAME, SUM(BYTES)/1024/1024 AS FREE_MB
FROM DBA_FREE_SPACE
WHERE TABLESPACE_NAME = 'SYSAUX'
GROUP BY TABLESPACE_NAME
) B
WHERE A.TABLESPACE_NAME = B.TABLESPACE_NAME;