Oracle 11.2.0.2里新增了一個新特性——用戶重命名(Rename User)，在這個版本之前要想重命名用戶，需要按用戶導出，再fromuser touser（imp）或remap_schem（impdp）。還可以通過修改數據字典user$的方式來重命名用戶，但這種方法可能會帶來風險。有了這個特性之后，可以通過alter user oldname rename to newname identified by "password";一條命令來重命名用戶。
下面來看測試過程，使用Oracle版本11.2.0.4
sys@ORCL>select * from v$version;
BANNER
-------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 - Production
1、創建測試用戶及測試表
sys@ORCL>create user sq identified by "sq";
User created.
sys@ORCL>grant connect,resource to sq;
Grant succeeded
sys@ORCL>create table sq.t1 as select * from dba_tables;
Table created.
2、執行alter user語句
sys@ORCL>alter user sq rename to zlx identified by "zlx";
alter user sq rename to zlx identified by "zlx"
*
ERROR at line 1:
ORA-00922: missing or invalid option
報錯無效的操作，原來是需要修改隱含參數"_enable_rename_user"
3、修改隱含參數"_enable_rename_user"，並以restrict模式重啟數據庫
sys@ORCL>alter system set "_enable_rename_user"=true scope=spfile;
System altered.
sys@ORCL>startup restrict force;
ORACLE instance started.
Total System Global Area 1620115456 bytes
Fixed Size 2253704 bytes
Variable Size 956304504 bytes
Database Buffers 654311424 bytes
Redo Buffers 7245824 bytes
Database mounted.
Database opened.
4、再次執行alter user語句，重命名用戶
sys@ORCL>alter user sq rename to zlx identified by "zlx";
User altered.
sys@ORCL>select count(*) from sq.t1;
select count(*) from sq.t1
*
ERROR at line 1:
ORA-00942: table or view does not exist
sys@ORCL>select count(*) from zlx.t1;
COUNT(*)
----------
2864
sys@ORCL>conn zlx/zlx
ERROR:
ORA-01035: ORACLE only available to users with RESTRICTED SESSION privilege
Warning: You are no longer connected to ORACLE.
sys@ORCL>conn / as sysdba
Connected.
sys@ORCL>alter system disable restricted session;
System altered.
sys@ORCL>conn zlx/zlx
Connected.
zlx@ORCL>select * from tab;
TNAME TABTYPE CLUSTERID
------------------------------------------ --------------------- ----------
T1 TABLE
從上面的結果來看用戶名重命名成功。
5、reset隱含參數"_enable_rename_user"並重啟數據庫
sys@ORCL>alter system reset "_enable_rename_user";
System altered.