数据库中规范化与反规范化设计的比较与分析

在大中型的软件系统中,数据库占据着举足轻重的地位。因此,数据库设计也就成为软件系统设计中的重要组成部分。文中首先论述了数据库逻辑设计中的关系规范化与反规范化的问题。然后针对相关问题,从提高数据库性能的角度,举例对比介绍了规范化设计技术和反规范化设计技术中几种常用的设计方法。并在此基础上,对这些方法的特点及方法的使用做了进一步的扩展讨论。最后,经分析得出,设计方法的选取还要根据工程中的实际需求来权衡。     

白蚁虫害仿真预测系统中反规范化的应用

白蚁虫害仿真预测系统中所应用的数据库首先都是基于规范化原则设计的,但考虑到效率的问题,就按照数据仓库中的反规范化原则对数据库进行了改进.本文在简要介绍了数据库中反规范化的应用后,详细地举出了一个用反规范化设计的数据库来讨论如何通过反规范化进行数据库设计优化.     

关系规范化理论及非规范化设计在数据库中的运用

本文首先介绍了数据库设计中的关系规范化理论，然后从提高数据库性能的角度，介绍了非规范化设计技术和几种常用的非规范化设计方法，并对这些方法的优缺点以及使用时的注意事项做了较为深入的论述。     

反规范化设计在园林技术专业教学资源库系统中的运用

数据库的设计对软件系统的运行起着非常重要的作用,合理的关系模式设计能够提高数据库的运行性能。在数据库设计中规范化设计理论是设计者常常遵循的原则,但是一味的追求关系模式范式的级别,满足了形式上的规范化往往会在实际使用中牺牲了运行效率,而适当的采用关系模式设计的反规范化手段,采用增加冗余列、增加派生列、重新组表和分割表等反规范化技术,合理处理好数据库的完整性,能够让数据库的设计更加合理,运行效率更高,更能满足实际应用的需要。该文以园林专业教学资源库数据库为例,阐述了反规范化技术在设计中的应用。     

非规范化在关系数据库设计中的应用

介绍了在关系数据库设计中的非规范化的概念和方法,即在数据库设计中适当地降低数据库的范式,以数据的冗余和不规则性来换取连接的减少以提高访问速度。并结合城市公共交通“一卡通”系统的数据库设计,分析了非规范化方法在实际问题中的应用,最后给出了非规范化处理的策略。     

数据库反规范化设计的探讨与实现

本文通过比较规范化与反规范化设计的特点与优劣，结合实例分析了反规范化设计的几个指导原则，阐明了反规范化设计的实现方法。     

实例分析关系模式的规范化与反规范化

规范化是减少数据冗余、设计合理的数据库的重要手段,是数据库课程的重点。由于涉及到关系数学理论,仅做理论讲解,很难使学生理解,尤其是高职层次的学生。本文通过一个关系模式不断分解、规范化的实例,采用逐步深入的方法解决数据库设计中存在的问题,使学生既掌握数据库设计的技能,也加深对函数依赖、规范化理论的理解。     

数据依赖与数据库规范化

任何一个数据库都会存在不同程度的数据冗余和更新异常等问题,为从源头上减少数据库的数据冗余和更新异常等问题,在数据库的设计过程中应进行规范化。通过对数据依赖和规范化理论进行研究,比较二者之间的关系来说明数据库的规范化过程,并以实例来分析规范化过程。分析比较发现规范化过程的实质是消除不合理的数据依赖。     

关系数据库的非规范化设计：在规范化设计和系统性能间平衡

介绍在关系数据库设计中规范化和非规范化设计的概念和方法,分析它们各自的优缺点,结合“书店管理系统”分析非规范化设计方法在实际问题中的应用。     

数据库的规范化理论与非规范化设计

关系数据库设计的目标就是要得到一组关系模式采组成一个最优的数据库模式，使得我们既不必存储不必晏的重复数据．又可以方便地查询数据。这组关系模式首先要用关系规范化理论规范化。构造好的逻辑结构，然后根据需要，从提高数据库性能的角度．进行非规范化处理。规范化和非规范化各有其优缺点，需要我们根据实际需求权衡处理。     

Assessing Ideational and Evaluative Skills and Creative Styles and Attitudes

This article describes the rationale for the multiphase creative problem solving process, and reports the findings from an empirical investigation conducted to facilitate the problem solving of managers. The ideational skills of the managers were assessed before and after training in a complete process of creative problem solving, along with their ideational attitudes, creative problem solving style (i.e., generator, conceptualizer, optimizer, or implementor), and evaluative skill (i.e., ability to recognize original ideas). The most important findings indicated that the training had a significant impact on the evaluative accuracy of the managers. They were significantly more accurate in their judgments about original ideas after training, both in their identification of original ideas and their recognition of unoriginal ideas. After training, the managers also gave more solutions and more original solutions to problems. Finally, several variables (e.g., the “preference for active divergence” attitude, and the conceptualizer process style) seemed to moderate the impact of training. Training was therefore effective, with specific effects that can be predicted from pre-training individual differences in attitudes and process style.     

Semantics and verification of monitors and systems of monitors and processes

In this paper we present a sound and complete semantics for the monitor concept of C.A.R. Hoare. First a method for specification of monitors, introduced by O.-J. Dahl, is reviewed. This method is based on the relation between the historic sequence of monitor procedure calls and the historic sequence of monitor procedure exits. Based on such specifications and our new monitor semantics we present a method by which it is possible to prove that a concrete monitor is an implementation of an abstract one. In the last part of the paper an axiomatic semantics for systems of concurrent processes and monitors is introduced. The method supports verification by separation of concerns: Properties of the communication to and from each process are proven in isolation by a usual Hoare style axiomatic semantics, while abstract monitors are also specified in isolation by the method reviewed in the first part of the paper. These properties of the components of the system are then used in a new proof rule to conclude properties of the complete system. Stein Gjessing received a Ph.D. (actually a Dr. philos.) from the University of Oslo (Norway) in 1985. Presently he is an Associate Professor at the Institute of informatics, University of Oslo, Norway. Dr. Gjessings research interests are in the area of concurrent and distributed programming, operating systems, formal specification and verification and programming languages.     

Integrating and automating analysis and optimization

The development of an interface coupling program on personal computers for an analysis software system such as ANSYS, SAP, etc. and an optimization software system, MOST, is presented. By controlling and directing the communications the interface coupler integrates the two programs while retaining their versatility and interactive features. The integrated system is used to solve a numerical example of active noise control for a three-dimensional enclosure, in which an energy density level of control points is minimized by adding the sound source to cancel the unwanted noise. The interface coupling program automates with relatively low cost the iterative process for designing an engineering system, remaining flexible in acoustical modelling and efficient in equation solving. Also, the coupling interface is developed in a general-purpose way so that it can be expanded easily to integrate more analysis software packages of different kinds.     

国内外标准法规比对分析系统设计与实现

为发现我国国家标准与国外发达国家标准法规的差距,从根本上提高我国国家标准的总体质量,提升我国产品的质量安全水平,以关键指标(因子)为核心,研究国内外标准法规比对的工作流程,利用面向对象的方法设计,实现了国内外标准法规比对分析系统。该系统适用于所有产品国内外标准法规的比对工作。     

高等院校行政分析与决策系统的设计与实现

为提高高等院校的管理水平和决策水平,充分利用校园网资 源,开发了高等院校行政财政分析与决策系统。解决了诸如数据的动态查询、自动生成报表 、网络环境下数据共享等技术问题,具有网上数据共享、图形界面友好和安全的保密措施等 特点。