例如,“部门名称”和“员工编号”的关系是“员工编号”→“部门编号” →“部门名称”,这不是直接相关,因此不满足第三范式的要求。 实体-关系模型(ER Modeling) 实体-关系模型(ER Modeling)是一种用于描述现实世界中实体以及它们之间关系的概念模型。这种模型被广泛应用于数据库设计中,有助于分析和理解数据结构,以及确
ERmodelingER模型 DatabaseDesign E-RModeling DatabaseDesign •Theideabehinddatabasedesign：•1）MappingtheRealWorldinformationtosomeAbstractconceptsandrelationsbetweenconcepts•2）Changingthoseconceptsandrelationstosomeformsofdatathatwecanmanipulate.•E-RModelingisawaytofulfillthetask.E-RModeling •Inthis...
Entity-Relationship Modeling - Foundations of Database Technology Springer, Berlin, 2000 Static integrity constraints are formulas of the hierarchical predicate logic (with abbreviations) in “normal definition frame” (may be deontic or strikt) Keys for identification of objects (esp. entity type...
ermodelinger模ermodelinger模型ermodelinger模型ermodelinger模型.ppt,Database Design E-R Modeling Database Design The idea behind database design: 1)Mapping the Real World information to some Abstract concepts and relations between concepts 2)Changing t
需求分析阶段,也被称为ER建模(entity-relationship modeling)阶段,也常被称为需求可视化,概念建模等。这一阶段数据库系统开发人员将协同需求方以ER图的方式对业务需求进行可视化展现。 本文将详细介绍(陈氏)ER符号体系,并在其中穿插一些具体实例讲解。 基本概念 ...
1) E R modeling ER建模2) ER model ER模型 1. An Extending ER Model for Data Warehouse Conceptual Modeling; 数据仓库多维建模的扩展ER模型 2. For ER model s property of capturing complex semantics and Star scheme s property of concision, this paper purposed a new multidimensional data model...
Problem Description: ER Modeling – A car rental company System A car rental company needs to create a database to manage their business operations. The company has a large fleet of cars that are rented out to customers for short-term and long-term rentals. The company has several ...
Database DesignE-R Modeling 阅读了该文档的用户还阅读了这些文档 29 p. 图片在商务网站的编辑和应用-课件(PPT演示) 8 p. 并列关系的句子的标点-课件(PPT演示) 48 p. 深圳协洋实业-课件(PPT演示) 11 p. 雷曼兄弟-课件(PPT演示) 29 p. 拉氏变换-课件(PPT演示) 40 p. 珍珠鸟(1)-课件(...
Impact of objected oriented thinking on ER modelingNo Abstract available for this paper.doi:10.1007/BFb0019910Charles W. BachmanSpringer, Berlin, Heidelberg
er图的属性还细分为复合属性、多值属性和派生属性、可选属性,同时还有用来表示联系的属性,称为联系属性。 复合属性(composite attribute):复合属性是指具有多个属性的组合,例如名字属性,它可以包含姓氏属性和名字属性,如下图: 复合属性也有唯一属性,例如学生的所在班级属性,由于多个年级都有班级,所以单单班级属性是不唯...