SELECT a.tablespace_name "表空间名",
    total "表空间大小",
    free "表空间剩余大小",
    (total - free) "表空间使用大小",
    total / (1024 * 1024 * 1024) "表空间大小(G)",
    free / (1024 * 1024 * 1024) "表空间剩余大小(G)",
    (total - free) / (1024 * 1024 * 1024) "表空间使用大小(G)",
    round((total - free) / total, 4) * 100 "使用率 %"
FROM (SELECT tablespace_name, SUM(bytes) free
        FROM dba_free_space
        GROUP BY tablespace_name) a,
    (SELECT tablespace_name, SUM(bytes) total
        FROM dba_data_files
        GROUP BY tablespace_name) b
WHERE a.tablespace_name = b.tablespace_name;

SELECT tablespace_name "表空间名称",
    file_name "数据文件存放位置",
    bytes/1024/1024/1024 "文件大小(G)"
FROM dba_data_files;