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Snailclimb merged 1 commit into from
Sep 12, 2023
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Update basis.md #2162

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4 changes: 2 additions & 2 deletions docs/database/basis.md
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Expand Up @@ -82,7 +82,7 @@ ER 图由下面 3 个要素组成：

> 【强制】不得使用外键与级联，一切外键概念必须在应用层解决。
>
> 说明: 以学生和成绩的关系为例，学生表中的 student_id 是主键，那么成绩表中的 student_id 则为外键。如果更新学生表中的 student_id，同时触发成绩表中的 student_id 更新，即为级联更新。外键与级联更新适用于单机低并发，不适合分布式、高并发集群; 级联更新是强阻塞，存在数据库更新风暴的风 险; 外键影响数据库的插入速度
> 说明: 以学生和成绩的关系为例，学生表中的 student_id 是主键，那么成绩表中的 student_id 则为外键。如果更新学生表中的 student_id，同时触发成绩表中的 student_id 更新，即为级联更新。外键与级联更新适用于单机低并发，不适合分布式、高并发集群；级联更新是强阻塞，存在数据库更新风暴的风险；外键影响数据库的插入速度

为什么不要用外键呢？大部分人可能会这样回答：

Expand Down Expand Up @@ -155,4 +155,4 @@ Tips：你应该更多地关注在使用场景上，而不是执行效率。
- <https://www.zhihu.com/question/24696366/answer/29189700>
- <https://blog.csdn.net/bieleyang/article/details/77149954>

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