您是否应该将自引用表列设为外键? [英] Should you make a self-referencing table column a foreign key?

问题描述

例如，要创建类别层次结构，您可以使用列parent_id"，它指向同一张表中的另一个类别.

For example to create a hierarchy of categories you use a column 'parent_id', which points to another category in the same table.

这应该是外键吗?有什么缺点/优点?

Should this be a foreign key? What would the dis/advantages be?

推荐答案

是的.确保您没有孤儿(没有父项的条目)，并且根据使用情况，如果您定义级联删除，当父项被删除时，其所有子项也将被删除.

Yes. Ensures that you don't have an orphan (entry with no parent), and depending on usage, if you define a cascading delete, when a parent is deleted, all its children will also be deleted.

缺点是会像任何其他外键一样对性能造成轻微影响.

Disadvantage would be a slight performance hit just like any other foreign key.

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