MySQL触发器在插入后更新计数 [英] MySQL Trigger to update count after insert

问题描述

我需要有关mysql触发器的一些帮助。我目前正在尝试整理一些代码并将部分处理工作转移到mysql数据库中，而不是运行2个查询和联接等...

I need some help with a mysql trigger. I am currently trying to tidy up some code and offload some processing to the mysql database rather than running 2 queries and joins etc...

当有人将视频插入到数据库，我希望更新类别中的视频计数。

When someone inserts into a video into a database, I would like the video count in the category to update.

因此，您可以指定类别ID。

So you specify the category id.

这是我到目前为止所拥有的，因此任何帮助都将是很好的，因为我似乎无法正确获取语法。

This is what I have so far so any help would be good as i just dont seem to be able to get the syntax correct.

CREATE TRIGGER 'db_videos'.'update_video_count'
AFTER INSERT ON 'videos' FOR EACH ROW
BEGIN
    UPDATE video_cat WHERE video_count = video_count + 1 WHERE video_cat = video_cat;
END;

推荐答案

您的where子句重复且不明确。如果我理解您的数据模型正确，请尝试：

Your where clause is duplicated and ambiguous. If I understand your data model correct, try:

CREATE TRIGGER 'db_videos'.'update_video_count'
AFTER INSERT ON 'videos' FOR EACH ROW
BEGIN
    UPDATE video_cat vc 
      WHERE video_count = video_count + 1 
      and NEW.video_cat = vc.video_cat;
END;

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