学生智能学习系统

PAGE\*romanPAGE\*romanii小学生智能学习系统摘 要最大范围内实现共享，产生了小学生智能学习系统。B/SMySQLServer2008关键词：B/S；java；JSPPupilsintelligentlearningsystemAbstractWiththeadvancementoftechnologyandtherapiddevelopmentofcomputernetworks,educationplaysinpeople'slivesisveryimportanttostartposition.Tomakepeople'slearningprocesscanbesubjecttogeographicalandtimeconstraints,makingteachingresourcescanbesharedwithinthemaximum,resultinginanonlineteachingsystem.TheWebsiteprimarilyforstudentsstudyingintheschooltoprovideanetworkplatformthatallowsstudentsanywhere,anytime,aslongastheplacewherethenetworkcanbee-learning,self-studytimearrangements,notonlybroketheschoolswhereinstructiontimelimitations,butalsosavestheresourcesofschools,butalsosavestimeforteachersandstudents,onlinecommunicationthatthefreedomofteachersandstudentsmoreconvenientchannelstosolvethestudentsfromlearningtolearnknowledge.Thedesignofthedevelopment isbasedonWiththeadvancementoftechnologyandtherapiddevelopmentofcomputernetworks,educationplaysinpeople'slivesisveryimportanttostartposition.Tomakepeople'slearningprocesscanbesubjecttogeographicalandtimeconstraints,makingteachingresourcescanbesharedwithinthemaximum,resultinginanonlineteachingsystem.TheWebsiteprimarilyforstudentsstudyingintheschooltoprovideanetworkplatformthatallowsstudentsanywhere,anytime,aslongastheplacewherethenetworkcanbee-learning,self-studytimearrangements,notonlybroketheschoolswhereinstructiontimelimitations,butalsosavestheresourcesofschools,butalsosavestimeforteachersandstudents,onlinecommunicationthatthefreedomofteachersandstudentsmoreconvenientchannelstosolvethestudentsfromlearningtolearnknowledge.Thedesignofthedevelopment isbasedonB/ Sstructure,JAdevelopmentlanguage,usingMyEclipsedevelopmentplatformandSQLServer2008databasedevelopment.Keywords:B/S;onlineteachingsystem;JSPII目录摘 要 iAbstract ii目录 I引言 1课题背景 2国内外研究现2本课题研究的意2本课题的研究方3可行性分3技术可行性 3经济可行性 4操作可行性 4相关理论知识介5系统开发环5结构 5Eclipse+MyEclip介 5SQLServer8绍 6简介 7需求分8用户角色分8功能模块划8性能需求 9总体设10系统功能图示10测试的主要内10业务流程分析 10数据流分析 12后台功能演示 14数据库表的设计与实14测试题答案信息表14课程文件信息表15课程信息表（kechens） 15新闻资讯信息(news) 16公告信息表（notices） 16试题信息表17系统用户信息表17数据库概念结构设计 18网站详细设21学生注册 22学生登录 22发布作业 23师生交流 24新闻管理 25公告栏管理模块的实25结论 26参考文献 27致谢 28附录A外文原文 29附录B外文译文 40附录C源代码 46华中科技毕业设计(论文)用纸华中科技毕业设计(论文)用纸PAGEPAGE101引言2120034的是一智能个十分重要的模块，小学生智能学习系统的建设是迫在眉睫的。以实现教学资源的优化与共享。学生通过网站可以随时随地学习或复习有有关学习内容，有了问题可以在线与教师、同学进行讨论学习。21力，有着相当大的帮助。本课题主要任务是以《小学生智能学习系统》为内容，研究与实现本课程的网络资以实现教学资源的优化与共享。学生通过网站可以随时随地学习或复习有有关学习内容，有了问题可以在线与教师、同学进行讨论学习。课题背景Internet国内外研究现状WebWebWebWebB/S目前国内各类小学也慢慢地将教学进行了信息化改造，这是大势所趋。本课题研究的意义当前，大力开发学生学习系统具有如下三方面的目的和意义。1.教育信息化建设的需要212.课程教学模式改革的需要当今世界，科学技术突飞猛进。面对新的形势，我们的教育观念、教育体制、教育结构、教学内容和教学方法相对滞后，因此，必须改革传统的教学课程教学模式和教学方法，借助多媒体技术和网络通信技术等，探索新型的课程教学模式和教学方法。3.新型人才培养的需要式学习，因而对于培养具有创新能力与合作精神的一代新人有至关重要的意义。本课题的研究方法（JSPSQLServer可行性分析证系统的开发是合理可行的。技术可行性MyEclipseTomcat统测试工具、SQL2008JSP。MyEclipseNetBeansSunONEStudioBorlandJbuilderJavaEclipse标准的插件集，包括Java开发工具（JavaDevelopmentTools，JDT）JavaIDEEclipse插件，它能扩展到任何语言的开发，甚至能成为图片绘制的工具。SQL2008XMLWebSQL2008完整性。JSP是在普通的Html中嵌入了Java代码的一个脚本，它由JSP容器（如Tomcat）Servlet，然后再调用JavacServletClassClassJSPSunJ2EETomcatServletTomcatJSPServletTomcatEclipsehibernate的框架实现本次毕业设计的要求。根据用户的要求，系统采用B/SB/SWebWebWeb现公文的流转。综上所述，系统的开发在技术上是可行的。经济可行性操作可行性正了解各位学生的学习情况，对下一步的教学进行更合理的布署。网即会使用本系统。综上所述，系统的开发在操作上是可行的。2相关理论知识介绍通过基于Internet互联网的动态WEB数据库技术，可以解决远程的数据传输与取远程的客户终端可以通过WEB页面提交请求查询远端的数据服务器上的信息时还可以向远端数据服务器的数据库中存储信息 以实现信息的共享，同时利用Internet技术可以降低软件的开发和部署成本，只要在服务器端装WEB应用就可以每个客户端都能浏览使用。系统开发环境B/SWEBJSP＋SQLServer2008＋MyElcipse结构B/S浏览器/服务器）结构，是随着InternetC/SWWW3B/SWWWScriptServletjavajspEclipse+MyeEclipseJavaJavaEclipseEclipseSWT/JFace，JavaMyeclipseEclipseJavaJavaXMLMyEclipse，Java,J2EEEclipse，MyEclipseMyEclipseEnterpriseWorkbenchMyEclipse）EclipseIDEJavaEEJavaEEHTML,Struts,JSP,CSS,Javascript,SQL,Hibernate。在结构上，MyEclipse在结构上，MyEclipse7EclipseMyEclipse块化，可以让我们在不影响其他模块的情况下，对任一模块进行单独的扩展和升级。简单而言，MyEclipseEclipseJavaEEEclipseMyEclipse6.0Eclipse。SQLServer8SQLServer2008Web性和安全功能。它支持EnglishQueryMicrosoftWeb用，SQLServer2008WebSQLServer2008最小。SQLServer2008SQLServerSQLServerSQLServerServer2008SQLServer2008为快速开发新一代企业级商业应用程序、为企业赢得核心竞争优势打开了胜利之门。完全的Web支持SQL2008提供了以Web标准为基础的扩展数据库编程功能。丰富的XML和Internet标准支持允许您使用内置的存储过程以XML格式轻松存储和检索数据。您还可以使用XML更新程序容易地插入、更新和删除数据。有了HTTP行全文搜索、以及通过Web进行自然语言查询。强大而灵活的基于Web的分析。SQL2008分析服务功能被扩展到了InternetWeb制多维数据。高度的可伸缩性和可靠性使用SQL2008可以获得非凡的可伸缩性和可靠性。通过向上伸缩和向外扩展的能力，SQLServer满足了苛刻的电子商务和企业应用程序要求。向上伸缩。SQL2008利用了对称多处理器(SMP)系统。SQLServerEnterpriseEdition最多可以使用32个处理器和64GBRAM。向外扩展。向外扩展可以将数据库和数据负载分配给多台服务器。可用性。用性。最快的进入市场时间SQL2008是Microsoft.NETEnterpriseServerSQL2005包括加速从概念到最后交付开发过程的工具。集成和可扩展的分析服务。有了SQL2008快速开发、调试和数据转换。SQL2008Transact-SQLVisualStudio化方式设计和编写数据库应用程序。简化的管理和调节。使用的同时轻松地在计算机间或实例间移动和复制数据库。JSP简介JSP(JavaServerPages)SunMicrosystemsWebWebWebJSPWebHTMLJavaJSPJSPWebJSPHTML格式返回给客户。程序片段可以操作数据库、重新定向网页以及发送email等等，这Plugin，无ActiveX，无JavaAppletFrame。需求分析用户角色分析根据网上学习的整个过程，整个系统要分两个角色：学生和老师（即管理员。功能模块划分学生子系统，师生互动系统（留言系统。（1）ID教师子系统部分的功能：管理员功能：管理员功能主要对后台数据进行管理，管理员登录后可以对新闻信息进行查看、修改和删除，还可以及时发表重要通知，资料上传下载，系统用户管理等。主要有以下功能。网站信息管理管理员可以发布大纲，网站简介等相关信息,对发布的信息进行查询、修改和删除。资料上传管理资料上传管理模块，和传各种资料供教师及学生下载学习系统用户管理对管理员、教师、学生的信息进行管理。可进行增删改查教师功能：资料上传下载、公告管理、个人信息管理。测试题管理编辑测试题目，有选择、填空、判断三种题型。可增删改查。作业批改管理作业批改情况。在线答疑教师在此处理学生在学习中遇到的疑问和难点。(4)测试分数查看的学习情况。(5)在线讨论教师可以发布讨论主题，供学生集体讨论，提升学生和教师的互动性。(6)资料上传下载教师发布学习资料等，完全实现了资源共享及无纸化。(7)公告管理教师发布各种通知公告，信息能即时到达学生。(8)个人信息管理教师修改个人信息。学生功能学生功能主要包括：通知公告浏览、联机测试、测试成绩查询、作业园地、在线提问、讨论交流、课程信息、资源下载、个人信息修改。通知公告浏览查看教师或管理员下发的各种通知公告，及时了解资讯联机测试学生在此可以看到教师发布的测试题并进行答题，答题提交后，系统自动评分。联机测试成绩查询学生可以查看自己每次测试的得分作业园地学生提交作业附件，教师即可下载后批改然后上传，学生即可看到批改后的作业。(5)在线提问间的交流，实现了师生之间的互动。讨论交流(7)课程信息(8)资源下载(9)个人信息学生修改个人信息性能需求数据安全性高。软件系统本身运行对计算机硬件平台和操作系统平台要求适中。总体设计系统功能图示例测试的主要内容想看看公布的信息，就点击公告栏。业务流程分析根据权限划分，用户共分为三类：管理员、教师、教师。（1）管理员业务流程图如图4.1.1所示。新闻管理新闻管理课程信息管理<<uses>><<extends>>系统用户管理<<uses>><<extends>><<extends>>资料上传管理管理员个人信息修改图4.1.1管理员业务流程图华中科技毕业设计(论文)用纸华中科技毕业设计(论文)用纸114.1.2试题管理试题管理成绩查看<<uses>><<extends>><<extends>>作业批改公告管理<<uses>><<extends>><<uses>><<extends>><<uses>>教师个人信息修改在线讨论在线答疑资源上传图4.1.2教师业务流程图4.1.3联机测试联机测试成绩查看<<uses>><<extends>><<extends>>作业园地浏览通知公告<<uses>><<extends>><<uses>><<extends>><<uses>><<uses>>学生个人信息修改在线提问讨论交流资源下载课程信息图4.1.3学生业务流程图华中科技毕业设计(论文)用纸华中科技毕业设计(论文)用纸PAGEPAGE12数据流分析根据前面的业务流图，得出各层的数据流图。TOP4.1.4P0P0F1学生操作信息学生学生操作结果学生F2教师操作信息教师小学生智教师操作结果教师管理员F3管理员操作信息管理员操作结果管理员图4.1.4TOP层数据流图4.1.5P1P1F1学生信息学习系统F6管理员操作结果F2课件信息D1学生信息表D2课件信息F3教师信息D3教师信息F4试题信息D4试题信息F5答疑信息D5答疑信息图4.1.5小学生智能学习系统管理数据流图4.1.6P2P2F1教师资料信息F2课件管理信息小学生智能学习系统D1表F3作业信息D2表F4疑问回复信息D3表F5考题信息D4表D5表图4.1.6小学生智能学习系统教师功能数据流图4.1.7所示。P3F1学生信息F2课件下载信息

小学生智能学习系统

D1 表F3F4F5

D2 表D3 表D4 表D5 表图4.1.7小学生智能学习系统学生功能数据流图华中科技毕业设计(论文)用纸后台功能演示管理员在登录成功后，就进入了后台管理。可以进行相应操作，如密码修改、管理员维护、留言管理、公告管理等。图4.1.8系统管理员功能示意图数据库表的设计与实现7分别是测试题答案信息表（answer）该表用于存储学生联机测试答题情况的信息，字段如表4.2.1所示。表4.2.1t_admin序 字段名 类型 长度精度小号 位

默认值 允许主键 说明空userIduserNameuserPw

int 4 √varchar 50 √varchar 50 √14华中科技毕业设计(论文)用纸华中科技毕业设计(论文)用纸PAGEPAGE15课程文件信息表（kcfiles）该表用于存储智能学习系统文件信息，字段如表4.2.2所示。表4.2.2t_doc序序号字段名类型长度精度小数位数默认值允许主键空说明1idint4√2mingchengvarchar50√3fujianvarchar50√4fujianYuanshimingvarchar50√5typevarchar50√6delvarchar50√课程信息表（kechens）该表用于存储课程信息，字段如表4.2.3所示。表4.2.3t_gonggao序字段名类型长度精度小数默认值允许主键说明号位数空1gonggao_idint4√2gonggao_titlevarchar50√3gonggao_contentvarchar8000√4gonggao_datavarchar50√5gonggao_fabuzhevarchar50√6gonggao_delvarchar50√7gonggao_one1varchar50√8gonggao_one2varchar50√9gonggao_one3varchar50√10gonggao_one4varchar50√11gonggao_one5datetime8√12gonggao_one6datetime8√13gonggao_one7int4√14gonggao_one8int4√新闻资讯信息表(news)该表用于存储新闻资讯的基本信息，字段如表4.2.4所示。表4.2.4t_liuyan序字段名类型长度精度小数默认值允许主键说明号位数空1liuyan_idint4√2liuyan_titlevarchar50√3liuyan_contentvarchar5000√4liuyan_datevarchar50√5liuyan_uservarchar50√公告信息表（notices）该表用于存储公告信息，字段如表4.2.5所示。表4.2.5t_picNews序字段名类型长度精度小数默认值允许主键说明号位数空1picNews_idint4√2picNews_titlevarchar50√3picNews_contentvarchar8000√4fujianvarchar50√5fujian_yuanshimingvarchar50√6picNews_datevarchar50√7picNews_one1varchar50√8picNews_one2varchar50√9picNews_one3varchar50√10picNews_one4varchar50√11picNews_one5datetime8√12picNews_one6datetime8√13picNews_one7int4√14picNews_one8int4√试题信息表（shiti）该表用于存储试题的基本信息，字段如表4.2.6所示。表4.2.6t_stu序字段名类型长度精度小数默认值允许主键说明号位数空1 stu_idint4√2 stu_xuehaovarchar50√3 stu_realnamevarchar50√4 stu_sexvarchar50√5 stu_agevarchar50√6 stu_cardvarchar50√7 stu_banjivarchar50√8 login_namevarchar50√9 login_pwvarchar50√10 delvarchar50√系统用户信息表（sysuser）该表用于存储系统用户的基本信息，字段如表4.2.7所示。表4.2.7t_tea序字段名类型长度精度小数默认值允许主键说明号位数空1tea_idint4√2tea_bianhaovarchar50√3tea_realnamevarchar50√4tea_sexvarchar50√5tea_agevarchar50√6login_namevarchar50√7login_pwvarchar50√8delvarchar50√数据库概念结构设计系统的主要实体有学生实体、信息实体、信息类别实体、教师实体、试题实体、学生问题实体等。4.3.1姓名姓名性别学号密码学生图4.3.1学生实体属性图4.3.2内容内容标题附件编号时间信息图4.3.2信息实体属性图4.3.3所示。编号编号名称信息类别图4.3.3信息类别实体属性图4.3.4姓名姓名性别编号密码教师图4.3.4教师实体属性图4.3.5题型题型章节题目知识点内容编号答案试题图4.3.5试题实体属性图4.3.6标题标题内容编号时间疑问图4.3.6学生问题实体属性图E-R4.3.7类别类别1管MNM学习课件教发NMNMN自测试题出题M学生教师1 1N M提出问题解答MNNM管理 管理管理图4.3.7总体E-R图华中科技毕业设计(论文)用纸网站详细设计系统主要包括发布作业、浏览作业、发布课件、下载课件、留言、公告栏，老师学生的登录系统。图4.4.1首页JAVA21华中科技毕业设计(论文)用纸学生注册该界面的主要是由一些文本框，选择控件，提交、重置、关闭按钮组成。图4.4.2学生注册publicStringstuReg(){TStustu=newTStu();stu.setStuXuehao(stuXuehao);stu.setStuRealname(stuRealname);stu.setStuSex(stuSex);stu.setStuAge(stuAge);stu.setStuBanji(stuBanji);stu.setLoginName(loginName);stu.setLoginPw(loginPw);stu.setDel("no");stuDAO.save(stu);return"successAdd";}学生登录登录界面它由一些基本的文本框、密码框、登录按钮组成，用户在该页面填写的用户名、密码来验证信息。该页面代码首先判断学生证、密码是否为空，如果任一项为空就跳出警告，提示用户输入完整信息。如果都不为空就先检查用户输入的用户名、密码跟数据库中的用户名、密码是否一登录的代码如下：Stringsql="fromTTeawheredel='no'andloginName=?andloginPw=?";Object[]con={userName,userPw};ListteaList=teaDAO.getHibernateTemplate().find(sql,con);22华中科技毕业设计(论文)用纸if(teaList.size()==0){}else{}

result="no";WebContextctx=WebContextFactory.get();HttpSessionsession=ctx.getSession();TTeatea=(TTea)teaList.get(0);session.setAttribute("userType",1);session.setAttribute("tea",tea);result="yes";布教案功能与此相似。TDocdoc=newTDoc();

图4.4.3 发布作业doc.setMingcheng(mingcheng);doc.setFujian(fujian);doc.setFujianYuanshiming(fujianYuanshiming);doc.setType("jiaocheng");doc.setDel("no");docDAO.save(doc);this.setMessage("操作成功");this.setPath("docMana.action");return"succeed";23华中科技毕业设计(论文)用纸师生交流师生交流是一个比较简单却是很直观的信息发布/存放系统，它提供了一个和浏览助、促进学生的学习。图4.4.4 师生交流TLiuyanliuyan=newTLiuyan();liuyan.setLiuyanContent(liuyanContent);liuyan.setLiuyanTitle(liuyanTitle);liuyan.setLiuyanDate(newDate().toLocaleString());liuyanDAO.save(liuyan);this.setMessage("留言成功");this.setPath("liuyanAll.action");return"succeed";TLiuyanliuyan=newTLiuyan();liuyan.setLiuyanContent(liuyanContent);liuyan.setLiuyanTitle(liuyanTitle);liuyan.setLiuyanDate(newDate().toLocaleString());liuyanDAO.save(liuyan);this.setMessage("留言成功");this.setPath("liuyanAll.action");return"succeed";24华中科技毕业设计(论文)用纸新闻管理管理员登录后可以添加新闻，包括标题、图片、内容；前台用户可以进行浏览，通过图片新闻可以让更多人学到和了解到相关知识。代码如下：TPicNewspicNews=newTPicNews();picNews.setPicNewsTitle(picNewsTitle);picNews.setPicNewsContent(picNewsContent);picNews.setPicNewsDate(newDate().toLocaleString());picNews.setFujian(fujian);picNews.setFujianYuanshiming(fujianYuanshiming);picNewsDAO.save(picNews);this.setMessage("操作成功");this.setPath("picNewsMana.action");return"succeed";公告栏管理模块的实现容。用户可以浏览网站及时信息。主要代码如下：TGonggaogonggao=newTGonggao();

图4.8公告gonggao.setGonggaoTitle(gonggaoTitle);gonggao.setGonggaoContent(gonggaoContent);gonggao.setGonggaoData(newDate().toLocaleString());gonggaoDAO.save(gonggao);this.setMessage("公告添加完毕");this.setPath("gonggaoMana.action");return"succeed";25华中科技毕业设计(论文)用纸华中科技毕业设计(论文)用纸PAGEPAGE27结论进一步研究开发所需要做的工作:步的完善.具体表现在以下方面:B/SC/S虽然提高了用户操作上的简单性.系统数据的安全性能有所折扣.对于网上广泛流传的ASP要添加图形数字验证码验证功能,以提高登录安全性.本文的主要工作总结:写中尽量减少出错数量，提高项目设计开发的效率。参考文献[1]孙卫琴,李洪成.《Tomcat与JavaWeb开发技术详解》.电子工业出版社,2003年6月[2]BruceEckel.《Java编程思想》.机械工业出版社,2003年10月FLANAGAN.Java.,20026月,.Java.,20028月[5]LEEANNEHTML4》.,20048月[6]飞思科《JSP.,20039[7],JSP.,20035月孙涌,20038月.,20022月[10]Brown等.JSP编程指南（第二版）.电子工业出版社,20033[11]JSP.,20045月[12]朱红.JSPWeb.,20019月[13].JSP.,20028月[14]美..ServletJSP..2002-10-1[15].JSP..2006-3-1杨青．JSP,[J]．1999,4．曹淑琴．JSP,[J]．2003,1．吴玉新．网站JSP[M]年[M]年刘禾、蔡锋．精通JSP[M]年AlbertoManuelRicart．Activeserverpages3exploitationenchiridion[M]社,2003年Ericserverpages[M]．北京：电子工业出版社[23]DaveMercer．JSP programme[M]．北京：人民邮电出版社年致 谢我受益匪浅，对顺利完成本课题起到了极大的作用。在此向她表示我最衷心的感谢！得以高效率的完成了所有问卷调查，获取了珍贵的数据资料！示深深的谢意！最后向在百忙之中评审本文的各位专家、老师表示衷心的感谢。附录A外文原文1、SoftwareEngineeringSoftwareisthesequencesofinstructions inoneormoreprogramminglanguagesthatcompriseacomputerapplicationtoautomatesomebusinessfunction.Engineeringistheuseoftoolsandtechniquesinproblemsolving.Puttingthetwowordstogether,softwareengineeringisthesystemticapplicationoftoolsandtechniquesinthedevelopmentcomputer-basedapplications.Thesoftwareengineeringprocessdescribesthestepsittakestodeelopthesystem.Webeginadevelopmentprojectwiththenotionthatthereisaproblemtobesolvedviaautomation.Theprocessishowyougetfromproblemrecognitiontoaworkingsolution.Aqualityprocessisdesirablebecauseitismorelikelytoleadtoaqualityproduct.Theprocessfollowedbyaprojectteamduringthedevelopmentlifecycleofanapplicationshouldbeorderly,goal-oriented,enjoyable,andalearningexperience.Object-orientedmethodologyisanapproachtosystemlifecycledevelopmentthattakesatop-downviewofdataobjects,theirallowableactions,andtheunderlyingcommunicationrequirement to define a system architecture. The data and action components encapsulated,thatis,theyarecombinedtogether,toformabstractdatatypesEncapsulationmeansthatifIknowwhatdataIwant,Ialsoknowtheallowableprocessesagainstthatdata.Dataaredesignedaslatticehierarchiesofrelationshipstoensurethattop-down,hierarchicinheritance and side ways relationships are accommodated. Encapsulated objects constrainedonlytocommunicateviamessages.Ataminimum,messagesindicatereceiverandactionrequested.Messagesmaybemoreelaborate,includingthesenderanddatatobeactedupon.Thatwetrytoapplyengineeringdisciplinetosoftwaredevelopmentdoesnotmeanthatwehavealltheanswersabouthowtobuildapplications.Onthecontrary,westillbuildsystemsthatarenotusefulandthusarenotused.Partofthereasonforcontinuingproblemsinapplicationdevelopment,isthatweareconstantlytryingtohitamovingtarget.Boththetechnologyandthetypeofapplicationsneededbybusinessesareconstantlychangingandbecomingmorecomplex.Ourabilitytodevelopanddisseminateknowledgeabouthowtosuccessfullybuildsystemsfornewtechnologiesandnewapplicationtypesseriouslylagsbehindtechnologicalandbusinesschanges.Anotherreasonforcontinuingproblemsinapplicationdevelopmentisthatwearen’talwaysfreetodowhatwelikeanditishardtochangehabitsandculturesfromtheoldwayofdoingthings,aswellasgetuserstoagreewithanewsequenceofeventsoranunfamiliarformatfordocumentation.Youmightaskthen,ifmanyorganizationsdon’tusegoodsoftwareengineeringpractices,whyshouldIbotherlearningthem?Therearetwogoodanswerstothisquestion.First,ifyouneverknowtherightthingtodo,youhavenochanceofeverusingit.Second,organizations will frequently accept evolutionary, small steps of change instead ofrevolutionary,massivechange.Youcanlearnindividualtechniquesthatcanbeappliedwithoutcompletedevotiontoonewayofdevelopingsystems.Inthisway,softwareengineeringcanspeedchangeeintheirorganizationsbydemonstratinghowthetoolstechniquesenhancethqualityofboththeproductandtheprocessofbuildingasystem.2、DataBaseSystem1、IntroductionThe development of corporate databases will be one of the most data-processingactivitiesfortherestofthe1970s.Datewillbeincreasinglyregardedas avitalcorporateresource,whichmustbeorganizedsoastomaximizetheirvalue.Inadditiontothedatabaseswithinanorganization,avastnewdemandisgrowingfordatabaseservices,whichwillcollect,organize,andselldata.Thefilesofdatawhichcomputerscanusearegrowingatastaggeringrate.Thegrowthrateinthesizeofcomputerstorageis greaterthanthegrowth inthesizeorpowerof anyothercomponentintheexplodingdataprocessingindustry.Themoredatathecomputershaveaccessto,thegreateristheirpotentialpower.Inallwalksoflifeandinallareasofindustry,databankswillchangetheareasofwhatitispossibleformantodo.Intheendofthiscentury,historianswilllookbacktothecomingofcomputerdatabanksandtheirassociatedfacilitiesasastepwhichchangedthenatureoftheevolutionofsociety,perhapseventuallyhavingagreatereffectonthehumanconditionthaneventheinventionoftheprintingpress.Somemostimpressivecorporategrowthstoriesofthegenerationarelargelyattributabletotheexplosivegrowthintheneedofinformation.Thevastmajorityofthisinformationisnotyetcomputerized.However,thecostofdatastoragehardwareisdroppingmorerapidlythanothercostsindataprocessing.Itwillbecomecheapertostoredataoncomputerfilesthantostorethemonpaper.Notonlyprintedinformationwillbestored.Thecomputerindustryisimprovingitscapabilitytostorelinedrawing,datainfacsimileform,photo-graphs,humanspeech,etc.Infact,anyformofinformationotherthanthemostintimatecommunicationsbetweenhumanscantransmittedandstoreddigitally.Therearetwomaintechnologydevelopmentslikelytobecomeavailableinthenearfuture.First,thereareelectromagneticdevicesthatwillholdmuchmoredatathandisksbuthavemuchlongeraccesstime.Second,therearesolid-statetechnologiesthatwillgivemicrosecondaccesstimebutcapacitiesaresmallerthandisks.Disksthemselvesmaybeincreasedincapacitysomewhat.Forthelongertermfuturethereareanumberofnewtechnologieswhicharecurrentlyworkinginresearchlabswhichmayreplacedisksandmayprovideverylargemicrosecond-access-timedevices.Asteadystreamofnewstoragedevicesisthuslikelytoreachthemarketplaceoverthenext5years,rapidlyloweringthecostofstoringdata.Giventheavailabletechnologies,itislikelythaton-linedatabaseswillusetwoorthreelevelsofstorage.Onesolid-statewithmicrosecondaccesstime,oneelectromagneticwithaccesstimeofafractionofasecond.Iftwo,three,orfourlevelsofstorageareused,physicalstorageorganizationwillbecomemorecomplex,probablywithpagingmechanismstomovedatabetweenthelevels;solid-statestorageoffersthepossibilityofparallelsearchoperationandassociativememory.Boththequantityofdatastoredandthecomplexityoftheirorganizationaregoingupbyleapsandbounds.Thefirsttrillionbiton-linestoresarenowinuse.inafewyear’stime,storesofthissizemaybecommon.Aparticularlyimportantconsiderationindatabasedesignistostorethedatasothatthecanbeusedforawidevarietyofapplicationsandsothatthewaytheycanbechangedquicklyandeasily.Oncomputerinstallationpriortothedatabaseeraithasbeenremarkablydifficulttochangethewaydataareused.Differentprogrammersviewthedataindifferentwaysandconstantlywanttomodifythemasnewneedsarisemodification ,however,cansetoffachainreactionofchangestoexistingprogramsandhencecanbeexceedinglyexpensivetoaccomplish.Consequently,dataprocessinghastendedtobecomefrozenintoitsolddatastructures.Toachieveflexibilityofdatausagethatisessentialinmostcommercialsituations.Twoaspectsofdatabasedesignareimportant.First,itshouldbepossibletointerrogateandthe data base without the lengthy operation of writing programs in programminglanguages.Second,thedatashouldbeindependentoftheprogramswhichusethemsothattheycanbeaddedtoorrestructuredwithouttheprogramsbeingchanged.Theworkofdesigningadatabaseisbecomingincreasingdifficult,especiallyifitistoperforminanoptimalfashion.Therearemanydifferentwaysinwhichdatacanbestructured,andtheyhavedifferenttypesofdataneedtobeorganizedindifferentDifferentdatahavedifferentcharacteristics,whichoughttoeffectthedataorganization,anddifferentusershavefundamentallydifferentrequirements.Soweneedakindofdatabasemanagementsystem(DBMS)tomanagedata.Databasedesignusingtheentity-relationshipmodelbeginswithalistoftheentitytypesinvolvedandtherelationshipsamongthem.Thephilosophyofassumingthatthedesignerknowswhattheentitytypesareattheoutsetissignificantlydifferentfromthephilosophybehindthenormalization-basedapproach.Theentity-relationship(E-R)approachusesentity-relationshipdiagrams.TheE-RapproachrequiresseveralstepstoprodureastructurethatisacceptablebytheparticularDBMS.Thesestepsare:DataanalysisProducingandoptimizingtheentitymodel.LogicalschemadevelopmentPhysicaldatabasedesignprocess.Developingadatabasestructurefromuserrequirementsiscalleddatabasesdesign.Mostpractitionersagreethattherearetwoseparatephasestothedatabasedesignprocess.Thedesignofalogicaldatabasestructurethatisprocessablebythedatabasemanagementsystem(DBMS)describestheuser’sviewofdata,andistheselectionofaphysicalstrsuchastheindexedsequentialordirectaccessmethodoftheintendedDBMS.Currentdatabasedesigntechnologyshowsmanyresidualeffectsofitsoutgrowthfromsingle-recordfiledesignmethods.Filedesignisprimarilyapplicationprogramdependentsincethedatahasbeendefinedandstructuredintermsofindividualapplicationstousethem.TheadventofDBMSrevisedtheemphasisindataandprogramdesignapproaches.Therearemanyinterlockingquestionsinthedesignofdata-basesystemsandtypesoftechniquethatonecanuseisanswertothequestionsomany;infact,thatoneoftenseesvaluableapproachesbeingoverlookedinthedesignandvitalquestionsnotbeingasked.Therewillsoonbenewstoragedevices,newsoftwaretechniques,andnewtypesofdatabases.Thedetailswillchange,butmostoftheprincipleswillremain.Therefore,thereadershouldconcentrateontheprinciples.2、DatabasesystemTheconceptionusedfordescribingfilesanddatabaseshasvariedsubstantiallyinthesameorganization.Adatabasemaybedefinedasacollectionofinterrelateddatastoredtogetherwithaslittleredundancyaspossibletoserveonormoreapplicationsinanoptimalfashion;thedataarestoredsothattheyareindependentofprogramswhichusethedata;acommonandcontrolledapproachisusedinaddingnewdataandinmodifyingandretrievingexistingdatawithinthedatabase.Onesystemissaidtocontainacollectionofdatabasesiftheyareentirelyseparateinstructure.Adatabasemaybedesignedforbatchprocessing,real-timeprocessing,orin-lineprocessing.Adatabasesysteminvolveapplicationprogram,DBMS,anddatabase.Oneofthemostimportantcharacteristicsofmostdatabasesisthattheywillconstantlyneedtochangeandgrow.Easyrestructuringofthedatabasemustbepossibleasnewdatatypesandnewapplicationsareadded.Therestructuringshouldbepossiblewithouthavingtorewritetheapplicationprogramandingeneralshouldcauseaslittleupheavalaspossible.Theeasewithwhichadatabasecanbechangedwillhaveamajoreffectontherateatwhichdata-processingapplicationcanbedevelopedinacorporation.Thetermdataindependenceisoftenquotedasbeingoneofthemainattributesofadatabase.Itimpliesthatthedataandtheapplicationprogramswhichusethemareindependentsothateithermaybechangedwithoutchangingtheother.Whenasinglesetofdataitemsservesavarietyofapplications,differentapplicationprogramsperceivedifferentrelationshipsbetweenthedataitems.Toalargeextent,data-baseorganizationisconcernedwiththerepresentationofrelationshipbetweendataitemsandrecordsaswellashowandwherethedataarestored.Adatabaseusedformanyapplicationscanhavemultipleinterconnectionsbetweenthedataitemaboutwhichwemaywishtorecord.Itcandescribestherealworld.Thedataitemrepresentsanattribute,andtheattributemustbeassociatedwiththerelevantentity.Wedesignvaluestotheattributes,oneattributehasaspecialsignificanceinthatitidentifiestheentity.Anattributeorsetofattributewhichthecomputerusestoidentifyarecordortupleisreferredtoasakey.Theprimarykeyisdefinedasthatkeyusedtouniquelyidentifyonerecordortuple.Theprimarykeyisofgreatimportancebecauseitisusedbythecomputerinlocatingtherecordortuplebymeansofanindexoraddressingalgorithm.Ifthefunctionofadatabaseweremerelytostoredata,itsorganizationwouldbesimple.Mostofthecomplexitiesarisefromthefactthatismustalsoshowtherelationshipsbetweenthevariousitemsofdatathatarestored.Itisdifferenttodescribethedatainlogicalorphysical.Thelogicaldatabasedescriptionisreferredtoasaschema.Aschemaisachartofthetypesofdatathatoneused.Itgivesthenamesoftheentitiesandattributes,andspecificstherelationsbetweenthem.Itisaframeworkintowhichthevaluesofthedata-itemscanbefitted.Wemustdistinguishbetweenarecordtypeandainstanceoftherecord.Whenwetalkabouta“personnelrecord”,thisisreallyarecordtype.Theresiaeatavalueswithit.Thetermschemaisusedtomeananoverallchartofalloft