如何在表中插入带有外键的行?

How to insert row in table with foreign key to itself?(如何在表中插入带有外键的行?)

问题描述

我有一个表，它本身有外键.列 parentid 是外键，它不能为 NULL.

I have table that has foreign key for itself. Column parentid is foreign key and it cannot be NULL.

如果我这样做INSERT INTO mytable(name) VALUES('name')，那么它说不能将NULL插入parentid.但是，如果还没有插入行，我可以为它设置什么值?！

if I doINSERT INTO mytable(name) VALUES('name'), so it says that can't insert NULL to parentid. BUT, what value I can set to it if no row was inserted yet?!

如何编写向该表添加行的脚本?

How I can write script that will add row to this table?

谢谢

推荐答案

一个技巧:有一个带有虚拟键的虚拟行，比如 99999.将它作为 FK 插入，然后将 FK 更改为其实际值.并在交易中完成.

A trick: Have a dummy row with a dummy key, say 99999. Insert with this as the FK, and then change the FK to its real value. And do it in a transaction.

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