++创建用户hillary,密码为window的用户,默认的表空间是users,临时表空间是temp
 create user hillary identified by window default tablespace users temporary tablespace temp;
 
++删除用户
 drop user user_name [cascade]; #如果被删除的用户拥有对象,则需要使用cascade关键字
 
++修改口令
 alter user user_name identified by new_password;
 password;   #仅能修改当前用户的口令
 
++锁定/解锁用户
 alter user user_name account [lock|unlock];
 
++修改默认表空间
 alter user user_name default tablespace new_def_tablespace [temporary tablespace new_temp_tablespace];
 
++给用户相应权限
 grant system_prifvilege[,system_privilege] to user_name [with admin option]; #with admin option表示将要授予系统权限的用户
 grant create session to hillary;  #授予create session privilege
 
++查看当前系统用户信息
 select username,password from dba_users;
 
++查看用户的系统权限
 connect user/password;
 select * from user_sys_privs;
 
++回收系统权限
 revoke system_privilege [,system_privilege] from user_name
 
++为用户授予对象权限
 grant object_privilege [(column_name)] on object_name to user_name [with grant option]
 #object_privilege表示对象权限,column_name表示对象中的列名称,object_name表示指定的对象名称,with grant option 允许该用户将当前的对象权限转授予其他用户.
 例:(1)为hillary用户授予对scott.authors表的select/insert/delete的对象权限.命令如下
 connect scott/password;
 grant select,insert,delete on scott.authors to hillary [with grant option];
 (2)为hillary授予对scott.authors表中first_name和phone列的更新权限.
 connect scott/password;
 grant update (first_name,,phone) on scott.authors to hillary;
++回收授予的对象权限
 revoke object_privilege on object_name from user_name
 connect scott/password; revoke select,insert on scott.authors from hillary;
 
++角色创建 / 查看角色信息
 create role role_name [identified by role_password];
 select * from user_role_privs;