消除XML亚强多值依赖引起冗余的一种分解方法

数据约束是数据库规范化理论的基础,不完全信息引入XML文档后,需要重新定义数据约束.本文基于子树信息等价和子树信息相容的概念给出了XML亚强多值依赖的定义;提出了弱键路径和XML亚强多值依赖弱范式的定义,通过实例分析XML亚强多值依赖引起数据冗余的原因,提出分解不完全XML文档满足XML亚强多值依赖弱范式的定理.研究成果可较好的处理不完全XML文档中存在XML亚强多值依赖引起的数据冗余问题,避免了数据冗余所带来的操作异常.

A decomposition method of eliminating redundant caused by XML inferior strong MVD

Data constraints are the basis of the database normalization,the introduction of XML documents with incomplete information,data constraints need to be re-defined.Based on the equivalence of the sub-tree information and the consistent of the sub-tree information,XML inferior strong multi-valued dependencies＇ definition was given.Weak keys and XML inferior strong multi-valued dependencies weak normal form were given.The reasons of data redundancies aroused by XML inferior strong multi-valued dependencies in incomplete XML document via the instance were analyzed,the theorem of decomposition for incomplete XML document for meeting XML inferior strong multi-valued dependency were presented.The production in this work can deal with data redundancies aroused by XML inferior strong multi-valued dependencies in incomplete XML document and avoid abnormal operation.