摘要
大量的无结构数据和复合对象是工程数据库的重要特征。本文介绍工程数据库管理系统ＥＤＢＭＳ／２对这两类复杂对象的管理策略及其ＳＱＬ查询。在ＥＤＢＭＳ／２中引入ＦＩＬＥ型属性和ＶＡＲ型属性用于存储形式多样的无结构数据，并采用用户自定义的方法，使之有多媒体数据管理功能。ＥＤＢＭＳ／２允许来自不同表中的一组记录通过联系构成一个复合对象。本文绘出的“路径表达式”为基于复合对象的复杂查询提供了强有力的工具。
ot of unstructure data and composite objects are the characteristic ofengineering data.In this paper,we present the strategies for complex objectmanagement and its SQL language in our own developed engineering databasemanagement system called EDBMS/2. Two kinds of new attribute type, FILE type andVAR type,are introduced to model various unstructured data.The user-define methodsare adopted to manage multimedia data convinently. In EDBMS/2,a group ofheterogenious records can be linked into a meaningful composite object. To faciliate thecomplex query in composite hierachy, we introduced the concept of 'path expression'.
出处
《计算机辅助设计与图形学学报》
EI
CSCD
1996年第1期36-41,共6页
Journal of Computer-Aided Design & Computer Graphics
