基于Vague数据库的代数查询语言  

Vague Databases Based Algebraic Query Language

作　　者：赵法信[1,2] 马宗民[1] 吕艳辉[1] 

机构地区：[1]东北大学信息科学与工程学院,辽宁沈阳110004 [2]通化师范学院,吉林通化134002

出　　处：《小型微型计算机系统》2008年第10期1893-1899,共7页Journal of Chinese Computer Systems

基　　金：教育部博士点基金资助项目(20050145024)资助;教育部新世纪优秀人才支持计划(NCET-05-0288)资助;吉林省教育厅科学技术研究项目(吉教科合字[2007]第214号)资助

摘　　要：基于Vague集理论的Vague关系数据库与其他模糊数据库一样,由于所含信息的模糊性,对应着现实世界的多种状态.虽然此类数据库能够更加真实地反映现实世界,但是在基于这些数据库的查询语言的有效性和计算过程的复杂性等方面却存在着一定的问题.本文基于Vague关系数据模型,对其代数查询语言中的选择、投影和连接操作进行了研究,指出基于一般Vague关系数据模型的查询语言中所存在的问题,并提出相应的解决方法,引入一种嵌套机制,对Vague关系模型进行了进一步扩展,进而对新模型查询语言中的三种操作在不同情况下进行了讨论,并给出了相应的定义.Based on vague set theory, the vague relational database which is the same as the fuzzy database, has a canonical interpretation as a set of regular databases because of the fuzzy information it contains. While such databases can be more truly reflect the real world, it is well known that their manipulations raise a number of problems, in particular with respect to the soundness of querying operations and the complexity of the evaluation process. In this paper, based on the vague relational data model, a query language including three operators such as selection, projection and join is explored. The problems exiting in the query language for the general vague relational data model are pointed out. In order to solve the problems, the vague relational data model is further extended through introducing a nesting mechanism. Finally, three operators in the query language are discussed in different situations and the corresponding definition is given.

关 键 词：模糊集 VAGUE集 vague关系数据模型 嵌套机制 代数查询语言 

分 类 号：TP311[自动化与计算机技术—计算机软件与理论]