Adding a relational interface to a nonrelational database

Today, thanks to more powerful machines and more robust data models, relational databases have gained broad industry acceptance. As relational databases grow in power and popularity, developers face pressure to convert legacy databases to this newer model. The author proposes a technique for doing so efficiently. The approach involves a bridge program that adds a relational software layer atop the nonrelational database management system. The interface translates the relational database management language into the nonrelational database management language to access the existing nonrelational database     

立体几何造型系统图形数据库

一个实用的、完整的几何造型系统必须有一个精心设计的图形数据库作为图形信息的存 贮和管理中心.本文以几何体的边界表示法为基础,提出了一个几何造型系统的图形数据库 设计方法,并介绍了该方法在UNIFY关系数据库管理系统上的实现及C语言接口设计.     

Access to indexed hierarchical databases using a relational querylanguage

An efficient means of accessing indexed hierarchical databases using a relational query language is presented. The purpose is to achieve an effective sharing of heterogeneous distributed databases. Translation of hierarchical data to an equivalent relational data definition, translation of a relational query language statement to an equivalent program that can be processed by a hierarchical database management system, and automatic selection of secondary indexes of hierarchical databases are investigated. A major portion of the result has been implemented, and the performance of the implemented system is analyzed. The performance of the system is satisfactory for a wide range of test data and test queries. It is shown that the utilization of the secondary index significantly enhances the efficiency in accessing hierarchical databases     

PDB: A pictorial database oriented to data analysis

The paper describes a new pictorial database oriented to image analysis, implemented inside the MIDAS data analysis system. Pictorial databases need expressive data structures in order to represent a wide class of information from the numerical to the visual. The model of the database is relational; however, a full normalization is not achievable, owing to the complexity of the visual information. The paper reports the general design and notes on the software implementation. Preliminary experiments show the performance of the pictorial database.     

Database Structure and Manipulation Capabilities of a Picture Database Management System (PICDMS)

The database structure and data manipulation capabilities of a generalized PICture Database Management System (PICDMS) are presented. They are based on a dynamic, stacked-image, logical database structure that uses gridded, rather than topological, data representation. A prototype PICDMS has been designed and implemented. A commercial version is being used as a generator of image processing programs. The system has novel capabilities for nonprogrammer users: it is able to 1) build multiple-variable databases from photographs and other two-dimensional data sources such as maps, drawings, etc., and 2) manipulate such data using simple logical commands. Physical organization and accessing strategies are outlined. A summary of the PICDMS data manipulation capabilities is presented and a subset of operations is illustrated with brief examples. A comprehensive example displays PICDMS capabilities and the programming advantages it possesses over other approaches.     

Progress in database search strategies

Retrieval speed and precision ultimately determine the success of any database system. This article outlines the challenges posed by distributed and heterogeneous database systems, including those that store unstructured data, and surveys recent work. Much work remains to help users retrieve information with ease and efficiency from a heterogeneous environment in which relational, object-oriented, textual, and pictorial databases coexist. The article outlines the progress that has been made in query processing in distributed relational database systems and heterogeneous and multidatabase systems     

An interface between object-oriented databases and relational databases

Currently relational databases are widely used, while object-oriented databases are emerging as a new generation of database technology. This paper presents a methodology to provide effective sharing of information in object-oriented databases and relational databases. The object-oriented data model is selected as a common data model to build an integrated view of the diverse databases. An object-oriented query language is used as a standard query language. A method is developed to transform a relational data definition to an equivalent object-oriented data definition and to integrate local data definitions. Two distributed query processing methods are derived. One is for general queries and the other for a special class of restricted queries. Using the methods developed, it is possible to access distributed object-oriented databases and relational databases such that the locations and the structural differences of the databases are transparent to users.     

The Pegasus heterogeneous multidatabase system

Pegasus, a heterogeneous multidatabase management system that responds to the need for effective access and management of shared data across in a wide range of applications, is described. Pegasus provides facilities for multidatabase applications to access and manipulate multipole autonomous heterogeneous distributed object-oriented relational, and other information systems through a uniform interface. It is a complete data management system that integrates various native and local databases. Pegasus takes advantage of object-oriented data modeling and programming capabilities. It uses both type and function abstractions to deal with mapping and integration problems. Function implementation can be defined in an underlying database language or a programming language. Data abstraction and encapsulation facilities in the Pegasus object model provide an extensible framework for dealing with various kinds of heterogeneities in the traditional database systems and nontraditional data sources     

Specification of spatial integrity constraints in pictorialdatabases

A model and a language for specifying spatial integrity constraints in pictorial databases are presented. Spatial integrity constraints are assertions about the correct behavior of database systems that specify acceptable database states and state transitions. They also serve as restrictions on positions occupied by objects in a picture. The language presented primarily uses pictures to specify constraints. The constraint pictures depict unacceptable database states. A data model provides the basic semantics for picture interpretation     

Example-based graphical database query languages

Several user-friendly graphical database query languages that let users formulate a query by specifying a graphically aided example on the screen are compared. One of the earliest such languages, M.M. Zloof's (1977) Query-by-Example, is described. Other languages discussed are Aggregates-by-Example, Summary-Table-by-Example, and Query-by-Statistical-Relational-Table for statistical and scientific databases; Time-by-Example for historical databases; Generalized-Query-by-Example for relational, network, and hierarchical databases; Office-by-Example, Formanager, the Natural Forms Query Language, and System-for-Business-Automation for office environments; and Picquery and Query-by-Pictorial-Example for pictorial (image) databases. The basic features, query specification and interpretation, object manipulation, query language constructs, and query processing techniques used in each of the languages are discussed     

A Generalized Query-by-Example Data Manipulation Language Based on Database Logic

The purpose of this paper is to introduce a Generalized-Query-By-Example (GQBE) data manipulation language (DML) that can be built on top of most existing databases (ie., relational, hierarchical, and network). The data manipulation language supports retrieval, insertion, deletion, and update operations and has a formal semantics based on database logic. It is also seen that GQBE can by used as a DML on external views of an integrated database. We also show the advantages of GQBE on heterogeneous databases over Zloof's QBE on relational external views.     

Fuzzy rough set techniques for uncertainty processing in a relational database

This paper concerns the modeling of imprecision, vagueness, and uncertainty in databases through an extension of the relational model of data: the fuzzy rough relational database, an approach which uses both fuzzy set and rough set theories for knowledge representation of imprecise data in a relational database model. The fuzzy rough relational database is formally defined, along with a fuzzy rough relational algebra for querying. Comparisons of theoretical properties of operators in this model with those in the standard relational model are discussed. An example application is used to illustrate other aspects of this model, including a fuzzy entity–relationship type diagram for database design, a fuzzy rough data definition language, and an SQL‐like query language supportive of the fuzzy rough relational database model. This example also illustrates the ease of use of the fuzzy rough relational database, which often produces results that are better than those of conventional databases since it more accurately models the uncertainty of real‐world enterprises than do conventional databases through the use of indiscernibility and fuzzy membership values. ©2000 John Wiley & Sons, Inc.     

A language for simple interactive retrieval from a database system

Query interaction with a database system requires, in general, some understanding of the content and structure of the database, and knowledge of a suitable query language to encode the request for data. These factors impose barriers against access to a database on a casual or irregular basis. To overcome such restrictions we have investigated the use of a pseudo-intelligent front-end retrieval system. This system was designed to be independent of any specific database management system, although a relational database structure was considered to be the most appropriate. A prototype version of the system has been set up to run on top of Logica's relational database management system RAPPORT and the IBM relational database system SQL. As a result of this experience we have developed an adaptable language to facilitate intelligent interaction between an end user and a database management system.     

Using Constraint Programming in Selection Operators for Constraint Databases

Constraint Databases represent complex data by means of formulas described by constraints (equations, inequations or Boolean combinations of both). Commercial database management systems allow the storage and efficient retrieval of classic data, but for complex data a made-to-measure solution combined with expert systems for each type of problem are necessary. Therefore, in the same way as commercial solutions of relational databases permit storing and querying classic data, we propose an extension of the Selection Operator for complex data stored, and an extension of SQL language for the case where both classic and constraint data need to be managed. This extension shields the user from unnecessary details on how the information is stored and how the queries are evaluated, thereby enlarging the capacity of expressiveness for any commercial database management system. In order to minimize the selection time, a set of strategies have been proposed, which combine the advantages of relational algebra and constraint data representation.     

Integrating relational and object-oriented database systems using a metaclass concept

This paper presents a specific approach of integrating a relational database system into a federated database system. The underlying database integration process consist of three steps: first, the external database systems have to be connected to the integrated database system environment and the external data models have to be mapped into a canonical data model. This step is often called syntactic transformation including structural enrichment and leads to component schemas for each external DBMS. Second, the resulting schemas from the first step are used to construct export schemas which are then integrated into global, individual schemas or views in the third step. In this paper we focus on the first step for relational databases, i.e., the connection of a relational database system and the mapping of the relational model into a canonical data model. We take POSTGRES as the relational database system and the object-oriented federated database system VODAK as the integration platform which provides the open, object-oriented data model as the canonical data model for the integration. We show different variations of mapping the relational model. By exploiting the metaclass concept provided by VML, the modelling language of VODAK, we show how to tailor VML such that the canonical data model meets the requirements of integrating POSTGRES into the global database system VODAK in an efficient way.     

RDF查询语言到SQL语言的转换原理及其实现方法

RDF查询语言的优点是具有语义性，缺点是对于海量信息的存储和查找的效率都很低．而关系数据库对海量信息的存储和查找的效率皆很高，但是其查询语言SQL却缺乏语义信息．为了使信息查询既有RDF的语义性又有关系数据库的高性能，提出将RDF查询语言到SQL语言的转换原理，并在此基础上实现一个对用户透明的、建立在关系数据库之上的RDF查询引擎．其优点是：可以利用关系数据库来存储和查询RDF信息，提高其海量存储和查找效率；对存储在不同的关系数据库中的关系数据，能够利用RDF的查找特性进行异质数据库之间的信息交换及信息融合．     

网站内容管理及个性化网页系统的研究与实现

针对现有内容管理系统在数据存储方面的问题,介绍了一个基于原生XML数据库和关系数据库的内容管理系统,这种方式充分利用了两种数据库的优势,提高了效率.同时应用数据挖掘技术,采用协同过滤算法,提供个性化网页服务,有助于赢得更多客户.     

OA系统与档案管理系统数据交换的研究与实现

Lotus Domino是当今办公自动化系统的主流开发平台之一,苏州大学的OA系统正是基于这个平台开发的。Domino自带一个非关系型数据库——文档型数据库,而苏州大学的档案管理系统的数据存储在SQL Server——关系型数据库中。因此要实现OA系统与档案管理系统的数据交换,必须要解决Domino和关系数据库的数据交换问题。本文利用ODBC实现Domino和关系数据库的互操作。