mysql - 更新 INSERT INTO... SELECT 上的外键

Question

我有以下语句将一个表(帖子)中的值插入到另一个表(对话)中:

INSERT INTO conversations (subject, user_id, notify_me, invite_only, real_name_only, max_post_length, last_updated_at, created_at, updated_at)
SELECT subject, user_id, notify_me, invite_only, real_name_only, max_post_length, thread_updated_at, created_at, updated_at FROM posts WHERE ancestry IS null;

每次插入后，我想更新 posts 的 conversation_id 列以指向新插入的 conversation 行。

实现这一目标的最佳方法是什么？

Answer 1

我认为你需要的是一个触发器:

DELIMITER $$

CREATE TRIGGER AFTER INSERT ON `conversations` FOR EACH ROW
BEGIN
    UPDATE posts
        SET posts.conversation_id = NEW.Id
        WHERE
            posts.subject = NEW.subject
            AND posts.user_id = NEW.user_id
            AND posts.created_at = NEW.created_at;
END$$