2. 数据模型¶

本书的第二部分涉及图形建模一般及实体-关系图特别。下图显示了章节之间的强依赖关系；各章节将假设读者掌握之前章节介绍的知识，如图所示。虚线轮廓表示书中其他部分的章节。

Part 2 of this book concerns graphical modeling in general, and entity-relationship diagrams in particular. The diagram below shows the strong dependencies between chapters; chapters will assume knowledge introduced in earlier chapters as implied by the graph. The dotted outlines indicate chapters from other sections of the book.