INSERT ...使用WHERE在重复密钥更新上?

本文介绍了INSERT ...使用WHERE在重复密钥更新上?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在执行INSERT ... ON DUPLICATE KEY UPDATE，但是我需要更新部分是有条件的，只有在某些额外条件发生变化时才进行更新.

I'm doing a INSERT ... ON DUPLICATE KEY UPDATE but I need the update part to be conditional, only doing the update if some extra condition has changed.

但是，此UPDATE上不允许使用WHERE.有什么解决方法吗?

However, WHERE is not allowed on this UPDATE. Is there any workaround for this?

我无法进行INSERT/UPDATE/SELECT的组合，因为这需要对复制进行工作.

I can't do combinations of INSERT/UPDATE/SELECT since this needs to work over a replication.

推荐答案

我建议您使用IF()来做到这一点.

I suggest you to use IF() to do that.

引用: conditional-duplicate-key-updates-with-mysql

INSERT INTO daily_events (created_on, last_event_id, last_event_created_at) VALUES ('2010-01-19', 23, '2010-01-19 10:23:11') ON DUPLICATE KEY UPDATE last_event_id = IF(last_event_created_at < VALUES(last_event_created_at), VALUES(last_event_id), last_event_id);