Oracle 新建删除用户并赋权

drop user user_name cascade;　　
如果提示 ORA-01940提示 “无法删除当前已连接用户”
（1）锁定用户
alter user XXX account lock;
（2）查询当前进程号
SELECT * FROM V$SESSION WHERE USERNAME=‘xxx‘；
(3)删除对应的进程
alter system kill session ‘xx,xx‘
(4)删除对应的用户
drop user user_name cascade

(1)、创建只读用户
create user read_user  identified by "password";
grant connect to read_user;
(2)、给用户赋予查询其他用户某几张表的权限
grant select on user_name.table_nameA to read_user

(3)创建同义词 (注意：如果不创建同义词，那么read_user用户查询表时，必须使用a.table这类的写法，不能直接用table.) 
grant create synonym to read_user
create or replace synonym read_user.table_nameA for user_name.table_nameA

elect * from dba_sys_privs where grantee=‘USER_NAME‘; 其中的username即用户名要大写才行。

select * from dba_users; 
select * from all_users; 
select * from user_users;//查看当前用户

select * from dba_sys_privs; 
select * from user_sys_privs; (查看当前用户所拥有的权限)

select * from dba_tab_privs; 
select * from all_tab_privs; 
select * from user_tab_privs;

select ‘Drop table ‘||table_name||‘;‘ from all_tables where owner=‘USER_NAME‘;(用户名要大写)

 select * from dba_roles;

select * from dba_role_privs; 
select * from user_role_privs;