以前执行了grant dba to 用户
查了一下dba角色中有一项 ：
DBA UNLIMITED TABLESPACE YES
现在执行了revoke dba from 用户
报错：ora-01950:对表空间XXX无权限
办法：
alter user username quota umlimited on tablespacename;
或者 grant resource to username 也可以
因为 grant resource to username 时 自动获得了有unlimited tablespace的系统权限
从online documents 找到这段话：
When you grant the DBA and RESOURCE roles to a user or role with Oracle7 release 7.2.2 or later, the user or role is also granted the UNLIMITED TABLESPACE system privilege. When you revoke either role from a user or role, the UNLIMITED TABLESPACE system privilege is also revoked. The UNLIMITED TABLESPACE can also be revoked independent of the DBA and RESOURCE roles.
感谢：