oracle用户，角色和权限

用户管理
权限的分类：系统权限，对象权限

创建用户
create user username
identified by password;

create user caozhi
identified by 123456;

权限
1.系统权限（创表，登录之类的）
2.对象权限

对象权限                表   视图   序列  过程 
修改(alter               √                √
删除(delete) )           √    √
执行(execute)                              √
索引(index)              √
插入(insert)             √    √
关联(references)         √    √
选择(select)             √    √      √  
更新(update)             √    √

系统权限
create sequence 组
create session 进程（登录）
create table 表
create view 视图
create peocedure 过程

给权限
grant 权限 to username;

例
grant create session ,create sequence,create table,create view ,create peocedure to username;

grant create session ,create table to caozhi;

角色
create role student;

创建student(caozhi,luyuan),teacher(fanxing,houlei)两组角色，给student 分配create session,给teacher分配create session,create table
1.创建用户
create user caozhi identified by 123456;
create user luyuan identified by 123456;
create user fanxing identified by 123456;
create user houlei identified by 123456;
2.创建角色
create role student;
create role teacher;
3.给teacher 和student 分权限
grant create session to student;
grant create session,create table to student;
4,将角色分配给用户
grant student to caozhi,luyuan;
grant teacher to fanxing,houlei;
5.测试

修改用户密码
alter user caozhi identified by 654321;

给caozhi用户开放emp数据表中empno列标题下的数据值
1.创建empno_view视图(scott)
create view empno_view
as
select empno
from emp;
2.给caozhi用户分配empno_view视图查看对象权限(scott)
grant select on empno_view
to caozhi;
3.切换caozhi 登录 进行测试
select *
from scott.empno_view;

收回权限
收回caozhi 用户查询scott.empno_view
在scott下
revoke select
on empno_view
from caozhi;
测试（caozhi）
select *
from scott.empno_view;

删除角色
drop role role_name cascade;