如何在mysql触发器中退出一系列If/else条件? [英] How do I exit a series of If / else conditions in a mysql trigger?

问题描述

我有一个触发器，用于检查更新期间某些字段是否发生了更改. 如果这些字段中的任何一个更改，我将更新另一个表.

I have a trigger that checks to see if certain fields changed during the update. If any of these fields changed I update another table.

我想一知道发生了什么变化，就立即打破if条件.

I'd like to "break" out of the if conditions as soon as I know that something changed.

是否可以在MySQL触发器中执行此操作?

Is there a way to do this within a MySQL Trigger?

我的作品行之有效，但效率似乎很低.

What I have works, but It seems inefficient.

CREATE TRIGGER profile_trigger
BEFORE UPDATE ON profile 
FOR EACH ROW
BEGIN 
DECLARE changed INTEGER;
   SET changed = 0;
IF STRCMP(NEW.first_name, OLD.first_name) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.last_name, OLD.last_name) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.suffix, OLD.suffix) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.title, OLD.title) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.gender, OLD.gender) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.street, OLD.street) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.street2, OLD.street2) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.city, OLD.city) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.state, OLD.state) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.zip, OLD.zip) <> 0 THEN 
   SET changed = 1;
ELSEIF STRCMP(NEW.home_phone, OLD.home_phone) <> 0 THEN 
   SET changed = 1;
ELSEIF NEW.date_of_birth <> OLD.date_of_birth THEN
   SET changed = 1;
END IF;
IF changed > 0 THEN
    update other_table set updated = CURRENT_TIMESTAMP where id = NEW.id;
END IF;
END; 
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推荐答案

这就是ELSEIF固有的工作方式.一旦MySQL找到任何符合条件的条件(即评估为TRUE)，它将不再评估IF..ELSEIF..ELSE链中的其他条件.

That's how ELSEIF works inherently. Once MySQL finds any condition that passes (i.e., evaluates to TRUE) it will not evaluate any further conditions in the IF..ELSEIF..ELSE chain.

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