在日常运维中，可以使用如下SQL语句显示Oracle表空间使用率：
SELECT a.tablespace_name,
ROUND(a.total_size) "total_size(MB)",
ROUND(a.total_size) - ROUND(b.free_size,3) "used_size(MB)",
ROUND(b.free_size,3) "free_size(MB)",
ROUND(b.free_size/total_size*100,2) || '%' free_rate
FROM (SELECT tablespace_name,SUM(bytes)/1024/1024 total_size
FROM dba_data_files
GROUP BY tablespace_name) a,
(SELECT tablespace_name,SUM(bytes)/1024/1024 free_size
FROM dba_free_space
GROUP BY tablespace_name) b
WHERE a.tablespace_name = b.tablespace_name;
执行脚本后，显示效果如下：
