Oracle tablespace viewing

1. view the size of all tablespaces   SQL> select tablespace_name, sum (bytes)/1024/1024 from dba_data_files 2 group by tablespace_name;   2. Used tablespace size SQL> select tablespace_name, sum (bytes)/1024/1024 from dba_free_space 2 group by tablespace_name;   3. Therefore, space can be calculated in this way.   Select a. tablespace_name, total, free, total-free used from (Select tablespace_name, sum (bytes)/1024/1024 total from dba_data_files Group by tablespace_name), (Select tablespace_name, sum (bytes)/1024/1024 free from dba_free_space Group by tablespace_name) B Where a. tablespace_name = B. tablespace_name;     4. The following statement shows the size of all segments. Select segment_name, sum (bytes)/1024/1024 from user_extents group by segment_name   5. How to put the result into a file in the case of command line. SQL> spool out.txt SQL> select * from V $ database; SQL> spool off