1. SQL¶

第 1 部分主要讲述 SQL, 这是一种与 关系数据库 交互的最流行语言,也是本书的主要焦点。本部分的章节组织方式允许根据讲师的期望方法以不同的顺序引入主题。下面的图表显示了章节之间的强依赖关系;章节将假设读者已经掌握了前面章节中介绍的知识,如图所示。虽然没有强依赖关系的章节仍然可能在提及其他章节时给出链接,但这些弱依赖关系对于理解引用的章节并不是关键的。

Part 1 of this book is all about SQL, the most popular language used for interacting with relational databases, the main focus of the book. The chapters in this section have been organized to allow topics to be introduced in somewhat different orders according to the instructor’s desired approach. The diagram below shows the strong dependencies between chapters; chapters will assume knowledge introduced in earlier chapters as implied by the graph. Chapters without a strong dependency may still refer to other chapters in passing, with a link to the chapter explaining the reference; these weak dependencies are not critical for understanding the referencing chapter.