Question

我有一个触发器，用于检查更新期间某些字段是否发生了变化。如果这些字段中的任何一个发生了变化，我会更新另一个表。

一旦我知道某些事情发生了变化，我就想“打破”if条件。

有没有办法在MySQL触发器中执行此操作？

我的作品，但似乎效率低下。

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; 
|

Answer 1

这就是ELSEIF本身的工作方式。一旦MySQL找到任何通过的条件（即，计算结果为TRUE），它将不会评估IF..ELSEIF..ELSE链中的任何其他条件。

Answer 2

尝试CASE声明......

SET changed = CASE
   WHEN STRCMP(NEW.first_name, OLD.first_name) <> 0 THEN 1
   WHEN STRCMP(NEW.last_name, OLD.last_name) <> 0  THEN 1
   WHEN STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0  THEN 1
   ...
   ELSE 0
END

Answer 3

一个怪物OR怎么样？它只意味着一个if语句;）

IF STRCMP(NEW.first_name, OLD.first_name) <> 0 or
   STRCMP(NEW.last_name, OLD.last_name) <> 0 or
   STRCMP(NEW.maiden_name, OLD.maiden_name) <> 0 or ...
   ...
   SET changed = 1;
end if;

IF changed > 0 THEN
    update other_table set updated = CURRENT_TIMESTAMP where id = NEW.id;
END IF;

......但是说真的，你的代码很好。没什么好担心的。 VoteyD是对的。

清除它的唯一方法是删除其中一些条件 - 尽管它可能不是一种选择。

如何在mysql触发器中退出一系列If / else条件？

3 个答案: