创建common user的时候报错：
$ sqlplus '/as sysdba'
SQL*Plus: Release 12.2.0.1.0 Production on Tue Apr 18 11:05:00 2017
Copyright (c) 1982, 2016, Oracle. All rights reserved.
Connected to:
Oracle Database 12c Enterprise Edition Release 12.2.0.1.0 - 64bit Production
SQL> create user c##backup_admin identified by backup_admin default tablespace users;
create user c##backup_admin identified by backup_admin default tablespace users
*
ERROR at line 1:
ORA-65048: error encountered when processing the current DDL statement in
pluggable database PLUG_TEST
ORA-65048: tablespace 'USERS' does not exist
SQL> show con_name
CON_NAME
------------------------------
CDB$ROOT
SQL> alter session set container=plug_test;
Session altered.
SQL> select tablespace_name,status,contents from user_tablespaces;
TABLESPACE_NAME STATUS CONTENTS
------------------------------ --------- ---------------------
SYSTEM ONLINE PERMANENT
SYSAUX ONLINE PERMANENT
UNDOTBS1 ONLINE UNDO
TEMP ONLINE TEMPORARY
UNDO_2 ONLINE UNDO
SQL>
原因：【默认表空间，临时表空间，必须在每个pdb中都存在】
While creating a common user, any default tablespace, temporary tablespace,
or profile specified using the following clauses must exist in all the containers belonging to the CDB:
DEFAULT TABLESPACE
TEMPORARY TABLESPACE
QUOTA
PROFILE
解决方法：
SQL> alter session set container=plug_test;
Session altered.
SQL> create tablespace users datefile '+da' size 133m autoextend on next 640k maxsize unlimited;
SQL> alter session set container=cdb$root;
Session altered.
SQL> create user c##backup_admin identified by backup_admin default tablespace users;
User created.
SQL>