INSERT ... ON DUPLICATE KEY UPDATE with WHERE?

INSERT ... ON DUPLICATE KEY UPDATE with WHERE?(INSERT ... ON DUPLICATE KEY UPDATE with WHERE?)

问题描述

我正在执行 INSERT ... ON DUPLICATE KEY UPDATE 但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 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?

我不能做 INSERT/UPDATE/SELECT 的组合，因为这需要在复制上工作.

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

推荐答案

我建议你使用 IF() 来做到这一点.

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

参考: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);

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