联结视图的更新问题

Discussion on Joinable View's Refreshment

在关系型数据库系统中，对视图的更新容易导致二义性和副作用，由联结运算（ｊｏｉｎ）定义的视图尤其如此．对这类视图的更新问题，利用参照完整性限制，讨论了避免副作用的问题，同时给出了主表和参照表的概念以及在此基础上克服二义性的方法．

In relational database system,the refreshment of view can easily lead to two selections and side effect.This also includes views defined by join.This article mainly discusses views of this kind.We discuss the question of avoiding side effect by use of complete Reference Restriction.At the same time we provide the concept of main table and the way of deleting two selections on this basis.