oracle如何查看表空间大小及使用情况

可以使用以下SQL语句来查看表空间的大小及使用情况：

1. 查看表空间的总大小、已使用空间和剩余空间：

SELECT tablespace_name,        ROUND(SUM(bytes) / 1024 / 1024, 2) AS total_space_mb,        ROUND(SUM(bytes - decode(maxbytes, 0, bytes, maxbytes)) / 1024 / 1024, 2) AS used_space_mb,        ROUND(SUM(decode(maxbytes, 0, bytes, maxbytes) - bytes) / 1024 / 1024, 2) AS free_space_mb   FROM dba_data_files  GROUP BY tablespace_name; 

2. 查看每个数据文件的使用情况：

SELECT file_name,        tablespace_name,        ROUND(bytes / 1024 / 1024, 2) AS file_size_mb,        ROUND(bytes - decode(maxbytes, 0, bytes, maxbytes) / 1024 / 1024, 2) AS used_space_mb,        decode(maxbytes, 0, bytes, maxbytes) / 1024 / 1024 AS max_space_mb,        autoextensible,        status   FROM dba_data_files; 

3. 查看每个表空间的数据文件及其使用情况：

SELECT tablespace_name,        file_name,        ROUND(bytes / 1024 / 1024, 2) AS file_size_mb,        ROUND(maxbytes / 1024 / 1024, 2) AS max_size_mb,        ROUND(bytes - decode(maxbytes, 0, bytes, maxbytes) / 1024 / 1024, 2) AS used_space_mb,        decode(maxbytes, 0, bytes, maxbytes) / 1024 / 1024 AS max_space_mb,        autoextensible,        status   FROM dba_data_files;