Oracle创建用户并授权，查看该用户拥有哪些系统权限

核心sql
查看用户有哪些系统特权
select * from session_privs;

授予connect,resource角色
grant connect,resource to test4;

收回权限
revoke unlimited tablespace from test4;

配额限制
alter user test4 quota 5m on users;
关于配额的几条简单命令，可以参照：
https://blog.csdn.net/weixin_42161670/article/details/102651036

实际操作

//创建用户test4
sys@ORCL>create user test4 identified by test4;

User created.

//连接用户test4，报错
sys@ORCL>conn test4/test4;
ERROR:
ORA-01045: user TEST4 lacks CREATE SESSION privilege; logon denied


Warning: You are no longer connected to ORACLE.

//授权test4予以create session权限
sys@ORCL>grant create session to test4;

Grant succeeded.

//连接用户test4，可以连接了
scott@ORCL>conn test4/test4;
Connected.
test4@ORCL>
test4@ORCL>
test4@ORCL>
//查看用户test4具有哪些系统权限
test4@ORCL>select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION

//用户test4创建表，报错说没有权限
test4@ORCL>create table t1(id number(10));
create table t1(id number(10))
*
ERROR at line 1:
ORA-01031: insufficient privileges

//授权test4予以create table权限
sys@ORCL>grant create table to test4;

Grant succeeded.

//这下终于可以建表了
test4@ORCL>create table t1(id number(10));

Table created.

//这下再查看用户test4具有哪些系统权限，多了一个create table权限
test4@ORCL>select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION
CREATE TABLE

//授权test4予以connect,resource角色
sys@ORCL>grant connect,resource to test4;

Grant succeeded.

//这下再查看用户test4具有哪些系统权限，明显多了很多，这些是赋予了connect，resource之后获得的系统权限
//UNLIMITED TABLESPACE表示对表空间的使用是无配额限制，对于一个普通用户来说，赋予此权限是很危险的，所以我们打算将此权限收回，并赋予一个有配额限制的权限

test4@ORCL>select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION
UNLIMITED TABLESPACE
CREATE TABLE
CREATE CLUSTER
CREATE SEQUENCE
CREATE PROCEDURE
CREATE TRIGGER
CREATE TYPE
CREATE OPERATOR
CREATE INDEXTYPE

10 rows selected.

//收回UNLIMITED TABLESPACE权限（注：revoke只对该角色里的UNLIMITED TABLESPACE有效，对其他权限无效）
sys@ORCL>revoke unlimited tablespace from test4;

Revoke succeeded.

//UNLIMITED TABLESPACE权限被回收了
test4@ORCL>select * from session_privs;

PRIVILEGE
----------------------------------------
CREATE SESSION
CREATE TABLE
CREATE CLUSTER
CREATE SEQUENCE
CREATE PROCEDURE
CREATE TRIGGER
CREATE TYPE
CREATE OPERATOR
CREATE INDEXTYPE

9 rows selected.

//赋予test4有配额限制的权限，使得该用户可以使用users表空间，但配额限制是5m

sys@ORCL>alter user test4 quota 5m on users;

User altered.