说明：  围绕一个典型而简单的例子，通过VB编程语言，从分析、建模、设计、编码等各个角度对三层体系与数据库进行了全面而详细的阐述，文中提供了全部源代码。
(Around a typical and simple example, through the VB programming language, from the analysis, modeling, design, coding, and various angles of the three-tier system and database, a comprehensive and detailed exposition, this paper provides the full source code.)