ER diagrams are visual tools that are helpful to represent the ER model. Peter Chen proposed ER Diagram in 1971 to create a uniform convention that can be used for relational databases and networks. He aimed to use an ER model as a conceptual modeling approach. Why use ER Diagrams? Here, ...
二.Association(关联) 先来看一下PD给association的定义:“An association is a connection between entities. In the Merise modeling methodology an association is used to connect several entities that each represents clearly defined objects, but are linked by an event, which may not be so clearly repre...
一、 构建ER模型图 1.新建一个图表,选择Extended,最后选择“Date Modeling”。 2.设计ER数据模型图,将打算设计的几张表,都画出来,注意所有需要的字段要写全,类型标明,并... 一款在线ER模型生成的工具: MySQL***,ER模型生成,通过DDL语句生成ER模型 我...
Conceptual data model:This stage is focused on understanding the high-level view of the data and the relationships between them. It is independent of any specific technology or database management system (DBMS). The main goal is to identify the main entities, their relationships, and th...
INTRODUCTION Entity-relationship (ER) modeling - conceptual database modeling technique Enables the structuring and organizing of the requirements collection process Provides a way to graphically represent the requirements Can be used as the foundation of data models ER diagram (ERD) - the result of ...
先来看一下PD给 association的定义:“An association is a connection between entities. In the Merise modeling methodology an association is used to connect several entities that each represents clearly defined objects, but are linked by an event, which may not be so clearly represented by another en...
Change the data model from one DBMS to another. Large model management. Model checking. Version management with possibility to archive or restore a version. Generate data dictionaries. ERBuilder Data Modeler Standard Features Visual data modeling ...
Supported DBMS include: MariaDB MySQL Microsoft SQL Server Microsoft Azure SQL database Oracle PostgreSQL SQLite Firebird Amazon Redshift Amazon RDS Key features: Visual data modeling Forward and Reverse Engineering Data Model Validation Data model documentation ...
先来看一下PD给association的定义:“An association is a connection between entities. In the Merise modeling methodology an association is used to connect several entities that each represents clearly defined objects, but are linked by an event, which may not be so clearly represented by another enti...
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...