具体过程如下：
1.系统用户SYS登录
conn? sys/password as sysdba
2.创建用户
create user username identified by password?
default tablespace user_data?
temporary tablespace user_temp;?
grant connect,resource to username;
3.建表 tableA,授权
GRANT ALL ON 用户A.tableA TO 用户B;
4.建同义词
CREATE SYNONYM 用户B.tableA FOR 用户A.tableA;