【摘要】 数据库模式直接决定和影响了数据的完整性、准确性和一致性 ,它对数据库的性能有致关重要的影响。关系数据库设计的目标就是要从各种可能的关系模式组合中选取一组关系模式来构成一个数据库模式 ,使得我们既不必存储不必要的重复信息 ,又可以方便地获取信息。在进行关系数据库设计时 ,一般是通过设计满足某一范式的模式来获得一个好的数据库模式 ,通常认为 3NF在性能、扩展性和数据完整性方面达到了最好的平衡 ,故一般数据库设计要求达到 3NF。更多还原

【Abstract】 The integrity, veracity, consistency of the data are determined and affected by database relation model which has crucial influence on the performance of a database. It’s the goal of the relation database design to find a set of relation model from the possible ones which make us needn’t save unneccessary duplicated information and can obtain the information expediently. In general, we obtain a good database model through design relation model which belongs to a certain formula. 3NF is considered to be the best tradeoff on performace, expansibility and integrity of data. So the design of a database is required to belong to 3NF in common.更多还原