查看 Oracle 表空间的使用情况

要查看Oracle表空间的使用情况，可以使用以下SQL查询：

SELECT
    df.tablespace_name AS "Tablespace",
    totalusedspace AS "Used MB",
    (df.totalspace - tu.totalusedspace) AS "Free MB",
    df.totalspace AS "Total MB",
    ROUND(100 * (totalusedspace / totalspace)) AS "% Used"
FROM
    (SELECT
         tablespace_name,
         ROUND(SUM(bytes) / 1048576) TotalSpace
     FROM
         dba_data_files
     GROUP BY
         tablespace_name) df,
    (SELECT
         ROUND(SUM(bytes)/(1024*1024)) totalusedspace,
         tablespace_name
     FROM
         dba_segments
     GROUP BY
         tablespace_name) tu
WHERE
    df.tablespace_name = tu.tablespace_name;

这个查询结合了dba_data_files和dba_segments视图，以提供每个表空间的名称、已用空间、空闲空间、总空间和已用百分比。确保你有权限访问这些视图，否则你可能需要联系数据库管理员。