PartTwoDatabaseDesignChapter6DatabaseDesignandE-RModelPart1.DBdesignphases(§6.1)requirementanalysis,conceptualdesign,logicaldesign,physicaldesignPart2.TheEntity-RelationshipModelbasicE-Rmodelmodelingelements(§6.2.1-6.2.3):entitysets,relationshipsets,attributesconstraints(§6.3.1-6.3.3):mappingcardinality,keys,participationconstraint(§6.6)weakentitysetsextendedE-Rmodel(§6.7)(§6.7.1-6.7.4)induceOOfeaturesintoE-Rmodel,thatis,specialization,generalization,attributesinheritance,constraintsongeneralization(6.7.5)aggregation:relationshipamongrelationships(§6.4)entity-relationshipdiagrams(§6.8)E-Rdiagram,i.e.,conceptualdesign,forbankingenterprisePart3.E-Rdesignissues(§6.5)whenapplyingE-Rmodeltomodeltheobjectsinrealworlds,someissues(considerationsandprinciples)shouldbeaddressed,toguaranteeDBSeffectivenessandefficiencyfordataPart4.Reductiontorelationalschemas(§6.9)mappingelementsinE-Rmodeltothatinrelationalmodels,i.e.conceptualschemainitiallogicalschemaDatabasedesignconsistsoftwosequentialphasesanalyzingofuserrequirementswhatdatashouldbestoredinthedatabasewhatoperations/transaction,suchasinsert,delete,updateandretrieveareneededtoconductedonthesedatadesigningofDBschemas,inaccordancewiththethree-levelofdataabstract(refertoFig.1.1)conceptualdesignlogicaldesign,atthelogicallevelandviewlevelphysicaldesign,atthephysicallevelrefertoFig.1.0.1Specificationofuserrequirements(需求分析说明书)April2011数据库应用系统DBAS设计DB,DBMS,users,applicationprogramsrefertoFig.6.0.2电信网管系统示意图DBAS设计refertoFig.6.0.3DBAS生命周期模型参照软件工程中软件开发瀑布模型原理，DBAS的生命周期由项目规划、需求分析、系统设计、实现与部署、运行管理与维护等5个基本活动组成根据DBAS的软件组成和各自功能，分为数据组织与存储设计、数据访问与处理设计、应用设计三条设计主线，分别用于设计数据库、数据库事务和应用程序根据数据库系统三级模式结构，DBAS设计阶段分为概念设计、逻辑设计、物理设计三个步骤，每一步设计内容涵盖了三条设计主线人机界面模块Fig.6.0.3DBAS生命周期模型6.2.1EntitySets（实体集，实体型）Aconceptualdatabasecanbemodeledasacollectionofentities,relationshipamongentities.Anentityisa“thing”or“object”intherealworldthatisdistinguishablefromallotherobjectse.g.acustomer,aloanaentityhasasetofproperties,suchascustome