show parameter undo;
desc dba_tablespaces;
select tablespace_name, contents from dba_tablespaces;

创建undo表空间
create undo tablespace myundotbs datafile '/u01/oracle/moree/myundotbs.dbf' size 10m;

切换undo tablespace
alter system set undo_tablespace=myundotbs;

drop表空间,只能drop非active状态的undospace
drop tablespace myundotbs;
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查看有哪些表空间:select * from v$tablespace;
查表空间都包含哪些数据文件:desc dba_data_files;
select file_name, tablespace_name from dba_data_files;
创建表空间:create tablespace paul datafile 'u01/oradata/wilson/paul01.dbf‘ size 10m;