> For the complete documentation index, see [llms.txt](https://hezhiqiang-book.gitbook.io/mysql/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13.md).

# 第十四节 约束

- [14.1 NOT NULL 约束](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13/not-null-yue-shu.md)
- [14.2 主键约束](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13/zhu-jian-yue-shu.md)
- [14.2 外键约束](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13/wai-jian-yue-shu.md)
- [14.4 UNIQUE 约束](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13/unique-yue-shu.md)
- [14.5 CHECK 约束](https://hezhiqiang-book.gitbook.io/mysql/di-yi-zhang/index-13/check-yue-shu.md)