SELECT V1.TABLESPACE_NAME "表空间名",
       ROUND(NVL(V1.SPACE,0)) "表空间大小(M)",
       ROUND(NVL(V1.SPACE,0)-NVL(V2.SPACE,0)) "已经使用空间(M)",
       ROUND(NVL(V2.SPACE,0)) "可用空间(M)",
       ROUND((NVL(V1.SPACE,0)-NVL(V2.SPACE,0))/NVL(V1.SPACE,0)*100,2) "已用百分比"
  FROM (SELECT TABLESPACE_NAME, SUM(BYTES)/1024/1024 SPACE FROM DBA_DATA_FILES GROUP BY TABLESPACE_NAME) V1,
       (SELECT TABLESPACE_NAME, SUM(BYTES)/1024/1024 SPACE FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME) V2
WHERE V1.TABLESPACE_NAME = V2.TABLESPACE_NAME(+)
ORDER BY V1.TABLESPACE_NAME