休眠:OnDelete 与级联 = CascadeType.REMOVE [英] Hibernate: OnDelete vs cascade=CascadeType.REMOVE

问题描述

@OnDelete(action=OnDeleteAction.CASCADE) 和 cascade=CascadeType.REMOVE

我在这里阅读:是否有 OnDelete 的等效注释在 JPA2使用 @OnDelete(action=OnDeleteAction.CASCADE) 级联将由 DB 处理，而使用 cascade=CascadeType.REMOVE 级联将由 ORM 处理(休眠).

I read here: Is there an equivalent annotation for OnDelete in JPA2 that with @OnDelete(action=OnDeleteAction.CASCADE) the cascade will be handled by the DB, while with cascade=CascadeType.REMOVE the cascade will be handled by the ORM (Hibernate).

1. 您能解释一下 Hibernate 处理与 DB 处理之间的区别吗?数据库"是如何做到的?

另外，我想知道我为什么要关心差异.我的意思是，我为什么要选择一种态度而不是另一种态度.

Also, I would like to know why should I care about the difference. I mean, why should I choose one attitude over the other.

最后一个问题是，查看 OnDelete javadoc 我想知道为什么它没有说明是什么以及为什么我应该使用它(顺便说一句，继承路径在哪里?).那么这些要点记录在哪里?

Last question is, looking at the OnDelete javadoc I was wondering why it says nothing about what is does and why I should use it (BTW where is the inheritance path?). So where are these points documented?

推荐答案

1-有些数据库支持级联选项，有些数据库不支持:如果数据库支持级联，那么 hibernate 将相应地创建模式并让数据库处理级联.

1-Some database support cascade option and some databases do not :If the database support cascade then hibernate will create schema accordingly and let database to handle cascading.

2-如果数据库句柄级联使用它，其他副hibernate必须查询数据库，这是性能损失.

2-If database handle cascade use it ,other vice hibernate have to query database and this is a performance lost.

3-不知道

这篇关于休眠:OnDelete 与级联 = CascadeType.REMOVE的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！