1.查看所有用户：
select * from dba_users where username='pjptdb';
select username from dba_users ;
select * from all_users;
select * from user_users;
2.采用oracle创建用户并授予dba权限
1）创建用户： create user pjptdb identified by pjptdb;
2）授予dba权限 grant connect,resource,dba to pjptdb ;
3.sqlplus远程连接
sqlplus dbuser/dbpassword@ip/sid
4.只赋予用户select inset表（而不是表空间）权限
步骤：
SQL> create user u1 identified by u1;
User created.
SQL> grant create session to u1;
Grant succeeded.
SQL> grant insert, select on table to u1;
5.改变用户默认使用的表空间
alter user username default tablespace userspace;
6.删除非空表空间
drop tablespace tablespace_name including contents and datafiles
7.创建表空间并赋予新的用户
create bigfile tablespace PJPTDBTS
datafile '/home/oracle/oradata/pjptdb/pjptdbts.dbf' size 500M autoextend on;
CREATE USER pjptusr IDENTIFIED BY pjptusr
alter user pjptusr default tablespace PJPTDBTS;
grant create table to pjptusr;
grant resource,connect to pjptusr
