Survey Management System-(2) design entity

Design entity (design database table)

By analyzing Requirement documents and static pages, you can understand requirements and abstract relevant entities.

Forward Engineering: designing entities, ing files → creating tables

Reverse Engineering: design table → ing file and Entity

When designing entities, consider the following issues:

1) How many entities are there?

Generally, a group of add, delete, modify, and query objects corresponds to one object.

2) What is the relationship between entities?

Generally, when a page references another object, it indicates that the object is associated.

3) What are the attributes of each object?

I. Primary Key.

Ii. Link Attributes. In the class diagram, an association is a line with two ends. Each end corresponds to an attribute that expresses the association. There are several ends pointing to this class, and this class has several correlated attributes.

Iii. General attributes. Analyze all related pages and find out the information to be filled in the form or displayed on the display page.

Iv. Special attributes: Attributes designed to solve a problem. For example, if you want to display the age, but do not design an int age field, but a date birthday field, the age is calculated in real time during display.

 

Note: The specific design of the entity in this project can refer to the design of complex and abstract entities related to survey, page, and question to understand the design process and improve the problem abstraction capability.

The summary of this article is from Xu peicheng's data collection system and Tang sunshine OA system. For more information, see http://blog.csdn.net/getclass/article/details/5178473.

investigation management system-(2) design entity