Mysql Workbench外键选项[Restrict，Cascade，Set Null，No Action]，它们做什么? [英] Mysql workbench foreign key options [Restrict, Cascade, Set Null, No Action], what do they do?

问题描述

在外键选项上进行更新和删除. 每个字段[限制，级联，设置为空，无操作]都有什么作用?

In foreign key options on update and on delete. What does each field [Restrict, Cascade, Set Null, No Action] do?

推荐答案

如果您一个一接:

对于更新和删除:

如果您尝试更新/删除父行:

if you try to update / delete the parent row :

限制:如果有子行，则什么也不能删除

Restrict : Nothing gonna be delete if there is a child row

级联:子行也将被删除/更新

Cascade : the child row will be delete / update too

设置空值:如果删除父级，则子级列将设置为空

Set Null : the child column will be set to null if you delete the parent

无操作:删除/更新将不涉及子行

No action : The child row will not be concern of the delete / update

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