首先,采用高层次的概念数据模型(conceptual data model)来组织所有与应用相关的可用信息。在概念层上,重点关注应用 … www.gispark.com|基于737个网页 2. 概念模型 如果是概念模型(Conceptual Data Model)的话,选 Variable characters ,要想生成数据库建表语句,还是转成具体数据库的物 … ...
点击“Tool”(工具)--->“Generate Physical Data Model"(生成物理数据模型)可以产生物理数据模型。暂时写到这里。
CDM(Conceptual Data Model,概念数据模型): 它主要是对现实世界的一种抽象表达,以实体、属性、关系等概念来描述业务领域中的数据结构和语义,重点在于表达业务概念和业务规则,通常独立于具体的数据库管理系统和实现技术。 PDM(Physical Data Model,物理数据模型)
1.定义、作用、适用场景 A conceptual datamodel (CDM) helps you analyze the conceptual structure of an informationsystem, to identify the principal entities to be represented, their attributes,and the relationships between them. A CDM is more abstract than a logical (LDM)or physical (PDM) data m...
第九课时:概念数据模型(Conceptual Data Model,CDM) 主要内容: 1.概念数据模型的定义、作用、适用场景 2.概念数据模型的组成元素及说明 3.概念数据模型的创建 4.概念数据模型的重点说明 1.定义、作用、适用场景 A conceptual datamodel (CDM) helps you analyze the conceptual structure of an informationsystem, ...
PowerDesigner 创建概念数据模型(CDM Conceptual Data Model) 1、创建概念模型 File --> New Model 2、主要操作功能介绍 2.1、 创建实体(Entity)。 2.2、 鼠标选择功能。 2.3、 实体关系(Relationship)。 3、创建CDM 3.1、 选中右侧中 Entity 图标,然后点击空白区域,出现下面这个方框: ...
Store data: 最基本的肯定是把数据从内存存到硬盘中去。 Access data: 包括查询,插入,删除和更新数据库。 Analyze data: 分析数据,比如outliers detection, complex aggregation. model data: 一般都会用 relational data modeling。还有object-oriented data modeling, first-order logic data modeling... 我没用过这...
Conceptual data models provide a link between reality as it is perceived by humans and the way in which reality will be represented in the database. A spatially extended entity relationship (SEER) conceptual data model is developed for an archaeological GIS which will make explicit any ...
概念数据模型(CDM–ConceptualDataModel).ppt,* After making index selections, it is often necessary to review the database design relative to the query demographics. There are often opportunities for performance enhancement which can result from denormal
The three levels of data modeling, conceptual data model, logical data model, and physical data model, were discussed in prior sections. Here we compare these three types of data models. The table below compares the different features: Feature...