开源数据库 百花齐放

在开源领域，有众多的开源数据库项目，媲美商业数据库的MySQL、企业级数据库PostgreSQL、嵌入式数据库Berkeley DB都为开源运动的深入发展添砖加瓦，在狭小的开源世界里，数据库也是百花齐放。     

利用ASP存取各种常用类型数据库

前言在Internet/Intranet网页上随处可见留言板、讨论组、网上投票、网上调查、聊天室等Internet功能模块，这些程序都是利用ASP(Active Server Page)与数据库技术结合而实现的。在Internet/Intranet上用的数据库大都是mdb数据库或SQL数据库，但是在企事业Intranet网中，各种版本的数据库已存在如DBF、DBC、Excel、文本数据库，这些数据库是由应用软件如办公自动化系统、财务软件等所生成，如果ASP能直接利用这些类型数据库，就不需要重新建立数据库，进一步实现企业数据共享，究竟这些数据库能不能直接被ASP使用，笔者经过长期…     

数据库垄断的成因及对策分析

学术数据库市场被少数几个出版商掌握，新的数据库商难以加入到竞争中来，因此导致了学术数据库市场的垄断问题。本文通过叙述学术数据库垄断的四个问题，即数据库定价的不合理、数据库许可权的滥用、经营者集中和数据库用户受限，提出通过开放获取、图书馆联合与立法保护来应对数据库市场的垄断问题。     

Oracle数据库中的废弃对象清理

本文介绍了利用ORACLE数据库系统本身的数据字典和功能，检查数据库对象的实际使用情况，查找出数据库废弃对象，并进行清理，提高数据库性能．完善了数据库的管理。     

基于OCI和ODBC异构数据库通用接口设计

文中分析了ODBC和OCI数据库接口的特点．为解决异构数据库的共享，提出了一种数据库应用程序连接数据库的方法——通用数据库接口。首先明确了通用数据库接口模块在系统中的位置，接着分析了该接口模块具备的具体功能，介绍了模块设计中的三个层次，然后总结了该接口模块的优点。封装了0DBC和OCI的通用数据库接口．可以实现异构数据库的互连，同时可以提高系统的性能。通过数据库调用函数来实现对异构数据库的操作，该通用数据库接口具有通用、简单、可扩展、可优化等特点。     

基于PHP技术的基因数据库Web平台设计

基因数据库是复杂的大型数据库。如何设计高效、简单、快速的操作平台是基因数据库发挥作用的关键问题、本文从对各种格式基因数据库的转换入手，就如何建立基因数据库连接，如何设置Web服务，实现Oracle数据操作等作了大量研究工作，借助PHP(Hypertext Preprocessor)设计了基因数据库Web平台，从而解决了基因数据库使用难的问题。     

nr数据库分析及其本地化

通过用NCBI的blastp程序对nr数据库与IPI数据库中属于人类的蛋白质序列进行比较，论证了nr数据库整合到蛋白质注释系统中的必要性。并在此基础上，设计方案实现了nr数据库的本地化，对nr数据库的记录进行了统计分析，提供了数据库的内部访问，为蛋白质拄释系统整合nr数据库做好了第一步工作。     

来者不拒，大小通吃——谈SQL Server的数据导入

数据库，顾名思义就是保存数据的仓库。数据可以是数据库本身产生的，也可以从其他的数据库（同种类型的数据库或异种类型的数据库均可）或是文件中导入。这里讨论SQL Server数据库数据导入的两种方法，以供大家参考。     

面向对象的数据库概述

指出应用的需求引出面向对象数据库的出现，面向对象数据库的定义，面向对象数据库与文件系统、关系数据库系统的区别，面向对象数据库的几种开发方法，面向对象数据库的应用领域及优缺点，最后简介面向对象技术与数据库技术结合展望。     

基于Servlet的Web数据库实现

介绍了Web与数据库的三种连接方式，为实现有效的Web数据库架构，主要讨论了应用J2EE的Web服务器端的开发组件Servlet和JDBC数据库连结技术实现Web与Orade数据库的动态连接，以及JDBC与Orade数据库的具体连接方法，实现Web数据库的结构模型。为提高Web数据库的存取效率，同时采用数据库连接池技术，实现基于Java的Web数据库，有效地解决和实现Web和数据库的集成，实现Web动态站点。通过实际运行表明，基于Serviet的Web数据库运行稳定、灵活，具有良好的可移植性。     

Deals with the Devil

Creating an accurate, well-constructed design is critical to ensuring the efficiency of the data base. To quickly complete a design project, however, designers are sometimes tempted to break the rules of data base design. This column explains why not following the basics of data base design will eventually lead to sinister problems with the data base.     

Data base design for computer-integrated structural engineering

The most likely architecture for an integrated engineering software system is a series of application programs operating off a shared central data base. The data base is the most critical part of the system. This article proposes a design for such a data base. The steps involved in data base, design are first reviewed, and several requirements for an effective structural engineering data base system are identified. A data base design based on a component-connection abstraction model and the object-oriented data model is then presented.     

Estimating record selectivities

In this paper we examine the problem of modelling data base contents and user requests. This modelling is necessary in analytic data base performance evaluation studies in order to estimate the number of records of a file that have to be retrieved in response to user(s) requests. The cpu, io, and telecommunication costs of the system are directly or indirectly expressed in terms of these quantities.We first show that certain assumptions-used for modelling data base contents, data placement on devices and user requests often are not satisfied in actual data base environments. Thereafter we provide more detailed modelling techniques based on a multivariate statistical model, and we demonstrate their use in improving data base performance.     

Modeling and analysis of data base organization: The doubly chained tree structure

The doubly-chained tree data base (file) organization is modeled and analyzed to obtain estimates of average access time (read-only) and total storage requirements. Macroscopic expressions are derived relating such performance measures to characteristic parameters of the specific data base, query or transaction traffic, storage devices and particular doubly-chained storage structure chosen. Important and generally applicable implementation-oriented aspects are considered. The model forms part of a prototype system for automatically analyzing and evaluating various data base organizations. The methodology and system are briefly outlined. Results for the doubly-chained structure using several real data bases are summarized, showing the rather large variability of performance as a function of both data base contents and complexity of queries.     

Logical data base design: A management-oriented approach

A logical data base consists of data definitions and data relationships. It is typically very large and complex even for a small organization, but it is generally designed in an ad hoc manner. However, several approaches have recently been proposed that allow for a systematic logical data base design.To make a data base more useful to the managers, it is imperative to encourage and obtain their involvement in the initial phase of the logical data base design. “Surface semantic models” are used in the logical data base design process to increase this involvement. A special type of this, called a “hierarchical external view model”, is proposed. It has been successfully used to develop a logical data base for the Department of Aging in Pennsylvania.     

传感器网络中具有负载平衡的移动协助数据收集模式

数据收集是无线传感器网络的一个基本功能.然而,现有的数据收集模式大都是基于静止基站的网络结构,导致基站周围的节点由于担负着网络内的所有负载而快速死亡,成为网络性能的瓶颈.研究如何利用移动基站收集数据来达到负载平衡.提出了一个利用移动基站协助数据收集的模式(movement-assisted data gathering,简称MADG),它将基站移动区域设置为缓冲区,首先将数据沿最短路径传输到缓冲区内,然后在基站移动的过程中进行数据收集.证明了缓冲区位置设置在距离中心时数据传输总能耗最少,并证明了存在一个缓冲区位置使得最大节点负载最小化,进而确定了同时考虑到能源消耗和负载平衡的基站移动区域.理论分析和实验结果表明,提出的数据收集模式在很大程度上降低了网络节点的最大负载,并且减少了数据传输能源中的消耗,分别比固定基站和同类工作的最大网络负载降低95%和80%以上.     

An integer programming formulation of computer data base design problems

Traditionally, computer data base design has been handled intuitively without the assistance of quantitative techniques. A systematic approach to data base design consists of these phases: (1) a mathematical problem statement; (2) problem reduction; (3) mathematical solution. This paper addresses the first phase (associated work on the other phases is briefly discussed) and demonstrates that certain data base design problems can be formulated as nonlinear, zero-one programs. The decision variables state which logical data base elements (entities and attributes) are represented in each subdivision (subfile) of the physical data base. Computational experience using cluster analysis for problem reduction and branch and bound for mathematical solution is reported. It is shown that a planned subdivision of the physical data base can yield noticeable operating cost improvements over conventional data base designs.     

Effects of different data base formats on information retrieval

This research examined the effects of three different data base formats on the information retrieval performance of users. Spatial, tabular, and verbal forms of two data base domains (airline and thesaurus) were constructed, along with questions that required users to search through the data base to determine the correct response. Three types of questions, compatible with the forms of the data bases, were designed--spatial, tabular, and verbal. The data indicate that users' responses to the questions are faster and more accurate when the format of the information in the data base matches the type of information needed to answer the question. Although the importance of matching data base format to query type may seem obvious, it would appear that the designers of most current data base systems have not taken this into account.     

无线传感器网络中一种能量有效的分簇算法

传感器网络中簇头与基站的通信方式可分为两种:多跳和单跳.如果采用多跳方式,靠近基站的簇头因传送数据较多而导致较早死亡;而在单跳方式中,远离基站的簇头因传送数据能耗太高而很快死亡.针对上述问题,提出一种基于非均衡分簇的数据收集算法,使靠近基站的簇的大小小于远离基站的簇.仿真实验表明,非均衡分簇的数据收集算法能有效地延长网络的生命周期.