OO模型中ODL语言的研究与实现

面向对象的数据库语言主要包括对象定义语言(ODL)和对象操纵语言(OML)。本文主要介绍以持久的面向对象程序设计语言为基础,研究和设计ODL语言的方法。     

FOOD：一个面向对象数据库系统

本文介绍一个面向对象数据库系统ＦＯＯＤ，重点描述ＦＯＯＤ的数据模型，应用编程语言，查询语言，授权模型和模式管理，并简要说明了系统的实现方法以及各功能模块，文末还对进一步的工作作了展望。     

Principles for persistent object access

Mechanisms for implementing persistent object access are described. Criteria and opportunities for standardization are identified. Principles are suggested for the development of an object-oriented database. These principles constrain the interaction of embedded DBMS constructs within the host programming language and indicate the appropriate use of existing language features vs. extension of the host language with new features to support persistence.     

一种支持对象物理聚集的综合方法

本文讨论了一种面向对象模型中同时支持按类查询和按复杂对象查询的新的对象物理聚集方法──综合法．该方法较常规聚集方法具有较佳的平均性能和最坏性能．     

面向对象数据库管理技术在IDSS中的应用

以一个智能决策支持中的专用面向对象数据管理系统OOSM为例，提出一套以提供开发支持为目的的面向对象数据管理模式，OOSM对象模型的定义充分借鉴了面向对象编程语言C＋＋的特性，永久性存储是采和了关系数据库系统与文件系统相结合的方式。介绍了OOSM提供的对象实例查询与操纵语言，这种语言是通过向客户提供通用模板代码的方式实现的。文中最后以作战方案对象为例，描述了上述模式的应用。     

一种适用于IC-CAD数据管理的对象语言及其编译器的设计与实现

当前,数据管理已成为各类计算机应用系统的瓶颈,而良好的数据模型是实现工程数据管理的关键。本文从描述复杂工程设计对象(以IC-CAD 为背景)的要求出发,设计了一种对象语言OL,试图在物理一级上给出一个对象的特性描述的全集,以便在对同一对象的不同阶段的设计时能共享数据,同时简化数据之间的转换,文中给出了OL 的语法要素及目标文件的结构,并描述了OL 编译器的实现。     

DODM：演绎型对象数据模型

演绎型对象数据库是演绎数据库和对象数据库结合的产物，它集成了演绎数据库的查询推理能力和对象数据库的强大建模能力。文中在已有的研究基础上较系统地研究演绎环境下对象数据模型，提出将类作为对象逻辑标识的集体和构造子；关系和集合为一类类构造子，体现了实体关系数据模型的思想；将型作为性质的集体，显式地区分类和型。引入型间偏相似关系来刻画继承语义，使得单继承、多继承和单调继承、非单调继承统一于型间偏相似关系，     

模糊关系数据库查询语言FSQL

模糊数据库是模糊信息处理系统的重要组成部分。本文以ＳＱＬ语言为基础，设计了模糊关系数据库查询语言ＦＳＱＬ。ＦＳＱＬ语言采用了模糊值模糊关系数据模型，提供了相应的模糊数据定义与模糊数据操纵功能。为了便于模糊信息的表示和管理，ＦＳＱＬ语言增加了模糊数据类型，如简单标量型、模糊标量型、简单数集、模糊数集等。另外，为了便于模糊查询，扩充了模糊比较库函数及自定义隶属函数。     

Design criteria for functional data bases

A functional data base is characterized as a collection of functions and its language as a collection of operators. The data base design criteria are established in terms of the functional properties, “redundancy” and “semantic content”. The behavior of data base operators is analyzed under these criteria to detect redundancies and compute the semantic content of a data model, to evaluate and compare data models. The correspondence between these criteria and the relational normalization theory is established.     

关系数据模型与面向对象数据模型的关系探讨

面向对象数据模型的应用打破了油田单一关系数据库体系架构。如何在面向对象数据模型和关系数据模型并存条件下构建和优化协调统一的数据库体系架构,是油田数据库建设的重要技术方向之一。本文从油田数据库应用的角度概要对比了关系数据模型和面向对象数据模型的特点,对关系数据模型和面向对象数据模型共存条件下建立油田数据库体系架构的可能性进行了探讨。     

持久对象访问的自动捕获

本文提出持久对象访问的自动捕捉技术，该技术是面向对象数据库系统在保持对象级的并发控制、版本管理和约束检查的条件下，实现持久对象与易变对象访问方式的一致性，进而实现面向对象数据库与程序设计语言的无缝结合的关键技术．     

View specification and manipulation for a semantic data model

Semantic data models are increasing in popularity and use, but they are also becoming increasingly complex and difficult to manage. In this paper we extend the definition of a semantic data model to give users the power to specify and manipulate views. Our model supports both high-level object-class views and high-level relationship-set views. To define these views, we extend the traditional method of view definition (through query formulation) to also include view definition by a dominant object class, by an independent object class, and by a relational object class. A set of operators to specify and manipulate views is also defined. These operators allow a user to create and destroy views, implode and explode views, hide and expose semantic-model elements. We also provide algorithms to extract an instance graph for a high-level object in a semantic-model view and to transform a semantic-model view hierarchy into an equivalent atomic model. Implications and applications of views in our model are also discussed.     

一个面向对象数据库系统的研究与实践

本文介绍了一个适用于ＣＩＭＳ、ＣＡＤ、ＡＩ和ＧＩＳ等领域的面向对象数据库系统ＷＨＹＭＸ．ＷＨＹＭＸ给出了聚合规范化和概括规范化的理论描述，提出了复杂对象的并发控制策略、存贮管理策略和对象管理方法．它支持嵌套事务处理和大对象的存贮管理．它在对象描述层下面增加了基于元组和面向值的操作，从而把面向对象模型与关系模型有机地结合在一起．     

基于规则的面向对象数据库查询语言

一、引言 八十年代中期兴起的面向对象数据库和知识库己成为当今数据库技术发展的两重要方向。自出现以来.它们沿着不同的道路独立发展,各自都取得了许多成果.知识库的研究是型的理论驱动的,着重研究基于规则的查询语言(如斯坦福大学的     

空间数据库的数据模型和查询语言

介绍了空间数据库的几种数据模型,分析各种模型的特点,在此基础上讨论了基于空间数据模型的空间数据管理、查询及查询语言。最后概括了将来的研究方向。     

Wcrl: A data model independent language for database systems

The need for data model independent languages for database systems has become apparent in recent years. They can be used for the conceptual level of a database system, for communication in a distributed database system, for data restructuring, and so on. This paper proposes a language,wcrl, to fill this need and compares it with the very few other languages which have been developed almost concurrently to fill the same need.     

COM组件接口方法参数的数据类型的选择

论述了在用 Visual C+ +建造 COM组件时 ,如何选择接口方法参数的数据类型的问题。结合客户程序是 ASP应用程序的情景 ,讨论利用 Visual C+ +和 ATL ,如何在组件程序的一端选择相应的数据类型。     

Object versioning in an ODMG‐compliant object database system

In this paper, we describe the design and implementation of the SOP Object Version System which is built upon an object database system, called SOP (SNU ODBMS Platform). SOP is fully compliant with ODMG‐93, a standard for object databases proposed by the Object Database Management Group (ODMG). To support object versioning in an ODMG C++ OML (Object Manipulation Language) environment, the SOP Object Version System provides a set of APIs (Application Programming Interfaces) as a class library. One important design goal of the SOP Object Version System was to achieve full compliance with ODMG‐93 standard. That is, in designing the class library, we tried to utilize the ODMG‐93 C++ OML interface as much as possible, while preserving its semantics as defined in ODMG‐93. Our object version model follows the basic functionalities of mainstream object version models. Although this approach burdens programmers with the management of the application‐specific version policy, it helps users to apply the SOP Object Version System to diverse application areas. Copyright © 1999 John Wiley & Sons, Ltd.     

An object deputy model for realization of flexible and powerful objectbases

In object-oriented databases, data and methods are combined by objects and their classes. Information redundancies are removed by the notions of class hierarchy and inheritance. This contributes the realization of high-performance systems. However, the flexibility of object structures still remains a problem due to its encapsulation feature. In this paper, we introduce an object deputy model which extends conventional object-oriented models with the concepts of deputy objects and deputy classes. A deputy object has its own identifier and may possess its own attributes and methods. It can also have attributes that are computed from values stored within its source object, and can be associated with methods generated from these of the source object. The inheritances are realized by switching operations, which make it possible to realize controllable, selective and dynamic inheritance structures. Schemata of deputy objects are defined by deputy classes which can be derived by an object deputy algebra. An object can have many deputy objects, and several objects can share a single deputy object. Thus, objects can be indirectly divided and combined through their deputy objects. We show that several difficult database problems, such as flexible views, objects with more than one role, object migration, and multiple inheritance become much easier in this model. The data-knowledge coordination model developed for the integration of distributed databases and knowledge-bases can also be realized easily by the object deputy model. Finally, we discuss several advanced database applications of this model, such as geographic databases, virtual office systems, and distant education systems.     

The living in a lattice rule language

This paper presents a rule-based query language for an object-oriented database model. The database model supports complex objects, object identity, classes and types, and a class/type hierarchy. The instances are described by ‘object relations’ which are functions from a set of objects to value sets and other object sets. The rule language is based on object-terms which provide access to objects via the class hierarchy. Rules are divided into two classes: object-preserving rules manipulating existing objects (yielding a new ‘view’ on objects available in the object base) and object-generating rules creating new objects with properties derived from existing objects. The derived object sets are included in a class lattice. We give conditions for whether the instances of the ‘rules’ heads are ‘consistent’, i.e. represent object relations where the properties of the derived objects are functionally determined by the objects.