关系数据库中关系模式的规范化

Standardization of Relation Pattern in Relation DataBase

关系数据库中的关系模式直接影响了数据库中数据的完整性、准确性和一致性,好的关系模式能避免数据冗余和操作异常。关系规范化是设计关系模式的依据,是围绕函数依赖进行的。其基本思想是一个关系只描述一个主题,遵从"一事一地"原则,不能把彼此没有直接关联的属性放在一起,这将会导致关系数据库性能变坏。关系规范化过程是不断分解关系的过程。根据关系中属性间函数依赖情况规定了若干标准,这就是所谓的1NF、2NF和3NF,还有更高的范式,通常认为3NF在性能、扩展性和数据完整性方面都达到了最好的平衡,故一般关系模式设计要求达到3NF。

The completeness, accuracy and compatibility concerning a pattern having had direct impact to the database.middle data in relation database. A good relation Pattern will be able to avoid the data redundancy and abnormal handling. That relation normalizes is the pattern basis designing relation , it is dependent on progress around function. Whose fundamental thought is that a relation describes a subject only, follow ＂to be related distance of one＇principle, it is can not direct put each other associative not at- tributes be in,this will be able to lead to the relation database function be changed into a dirty trick together. Concerning normalized process is the process breaking up relation unceasingly.Attribute room function be dependent on condition has stipulated some standards in basis relation,this has been called I NF,2 NF and 3 NF, has still had higher canonical form, has thought that 3 NF has all reached balancing best, reaching therefore the sort concerns pattern design call for 3 NF in the field of the function, extended and data completeness generally.