Question

我有以下语句将值从一个表（帖子）插入另一个表（对话）：

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conversation_id的{{1}}列，指向新插入的posts行。

实现这一目标的最佳方式是什么？

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$$

在INSERT INTO ... SELECT上更新外键

1 个答案: