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';
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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
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满足account_number='111222333' 和 account_type='savings'的所有记录的account_number字段改为３００;