1. 首先,需要对Scott账户进行解锁,输入:alter user scott account unlock;这时,提示scott账户过期并且密码过期(expired);

2. 然后,查看scott账户有效期,输入:select * from dba_profiles s where s.profile = 'default' and resource_name = 'password_life_time';

3. 接着,设置scott账户的有效期为无限,输入:alter profile default limit password_life_time unlimited;

4. 最后,修改scott账户的密码为root,输入:alter user scott identified by root。