oracle中查看用户权限

1.查看所有用户：
  select * from dba_user;
  select * from all_users;
  select * from user_users;
2.查看用户系统权限：
  select * from dba_sys_privs;
  select * from all_sys_privs;
  select * from user_sys_privs;
3.查看用户对象权限：
  select * from dba_tab_privs;
  select * from all_tab_privs;
  select * from user_tab_privs;
4.查看所有角色：
  select * from dba_roles;
5.查看用户所拥有的角色：
  select * from dba_role_privs;
  select * from user_role_privs;

6.查看角色所拥有的权限:

  select * from role_sys_privs;

  select * from role_tab_privs;

7.查看所有系统权限

  select * from system_privilege_map;

8.查看所有对象权限

  select * from table_privilege_map;

以上是在Oracle中查看用户权限 ，
在DB2中为：
  select * from syscat.dbauth
  或者
  get authorizations