一道题，大家帮忙解决方法

一道题，大家帮忙
试写出ORACLE系统对下述语句的执行过程： 
UPDATE bank_table SET account_number=300 WHERE account_number='111222333' AND account_type='savings';

------解决方案--------------------------------------------------------
对account_number='111222333' 和 account_type='savings'列的account_number改为300
------解决方案--------------------------------------------------------
当 bank_table 的account_number='111222333' AND account_type='savings'时, account_number=300
------解决方案--------------------------------------------------------
满足account_number='111222333' 和 account_type='savings'的所有记录的account_number字段改为３００;