中文摘要：

关系数据库模式设计的好坏直接影响到整个数据库应用系统的性能,应遵循关系规范化理论,而派生属性是数据库中的衍生数据,是一种特殊属性。阐述了派生属性的四种类型,并用实例详细分析了其存储方式、修改方法及方法的好处,即不分解有派生属性的第二范式关系,运用表触发器修改计算方法简单的派生属性,运用存储过程修改计算方法复杂的派生属性,既避免修改异常,又不会降低数据库修改的效率。

英文摘要：

The design of relational database schema directly affects the performance of database application system,and relation normalization theory should be followed.The derived fields,derived data in database,are special ones.Stated four types of de rived fields and through examples analyzed the method of their storage,updates,and the advantages of the method,i.e.,do not break up the relation with derived fields,use table triggers to update the simple derived fields and stored procedures to the com plex derived fields.The method does not cause the abnormity of updates,and not decrease the performance of database opera tions either.