Create a database with an object relationship diagram (nothing can be done, repost)

Modeling a database using an object relationship diagram
(A liang @ Cactus studio August 14, 2001)
I. Overview
It is very likely that you are planning a database-driven website, and you are almost certain that you have browsed the database-driven website. In the past, some websites relied on CGI scripts and text file storage to achieve data persistence, but now we can access a large number of different relational databases, object-relational databases, and object-oriented databases.
For Web applications, relational databases are a powerful support tool, thanks to their high availability and performance. In addition, relational databases are relatively easy to use. It is not difficult to find a database system with complete functions, open source code, and running on multiple platforms. You can use Perl, Java, PHP, and other server-side scripting languages to link relational databases with Web sites.
With the development of the website scale, it is increasingly dependent on databases, usually relational databases. A large number of pages and services need to write information to the database table or extract information from the database. For most websites, database tables quickly become a key part of the website architecture and the hub of website operation. To facilitate and easily manage large volumes of data, user accounts, news, content, and statistics can all be stored in the Relational Database Management System (RDBMS ).
Using graphs to manage data models is efficient and convenient. For RDBMS, an image describing a data model is usually called an Entity Relationship Diagram (ERD ). Using ERD to describe the data model can help you define data requirements in advance, so that you can make effective plans for future changes and easily improve the planning as the website develops.
This article introduces ERD modeling tools and concepts. The article provides some graph examples, but they do not aim to provide accurate or comprehensive data design examples. They are designed to use two modeling tools as an example to introduce data modeling symbols. There are significant differences between different tools, but they have the same basic concept. The legends in this article are obtained from the trial versions of PowerDesigner and Visio 2000 Professional. You can find links to these tools and other similar products at the end of this article.
2. Are you using modeling tools?
Many small websites use the ascii SQL (Structured Query Language) script file for data modeling. This approach is most effective when there are few developers or ideally only one person. However, data models will soon evolve into a complex structure-in this CASE, CASE (Computer Aided Software Engineering, Computer-Aided Software design) tools, graphs about all data information, and a centralized knowledge base can greatly help you manage the data layer of a Web site.
2.1 When to use SQL?
Even if you want to use SQL to directly manage the data mode (physical database), the graph can effectively help you understand and improve the system. However, if you have a very limited budget or time, you may not be able to use a complex new modeling tool. On the contrary, in this case, you should use a simple graphical tool to record the basic situation of the data mode and then gradually convert it to a complex data modeling tool.