MySQL用触发器同步两张表

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本文介绍如何使用MySQL触发器在两个表(person和个人扩展表person_ex)间同步数据变更，特别是针对sex字段为'M'的情况。文章包括创建触发器的具体SQL语句及测试用例。

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在MySQL环境下面，建立相关触发器，在两个表之间相关sql，希望能帮到大家

1.建person表

CREATE TABLE `person` (
  `id` int(11) DEFAULT NULL,
  `name` varchar(256) DEFAULT NULL,
  `sex` char(16) DEFAULT NULL
)

建person_ex

CREATE TABLE `person_ex` (
  `id` int(11) DEFAULT NULL,
  `name` varchar(256) DEFAULT NULL,
  `sex` char(16) DEFAULT NULL
)

2.实现的目标当person新增一条记录，更新一条记录或者删除一条记录，person_ex中sex字段为M的记录跟着改变

sql代码如下：

创建插入触发器

create trigger person_trigger AFTER insert on person  for each row 
begin set @x = "hello trigger";
IF new.sex = 'M'
THEN
       INSERT INTO person_ex(id,name,sex) VALUES (New.id,new.`name`,new.sex);
END IF;
end;

创建更新触发器：

create trigger person_trigger_update AFTER UPDATE on person  for each row 
begin set @x = "trigger UPDATE";
IF new.sex = 'M'
THEN
DELETE from person_ex where person_ex.id = new.id;
       INSERT into person_ex SELECT * from person where person.id = new.id;
END IF;
end;

创建删除触发器：

create trigger person_trigger_delete AFTER DELETE on person  for each row 
begin set @x = "trigger DELETE";
       DELETE FROM person_ex where person_ex.id = old.id;
end;

3.测试SQL代码：

INSERT into person (id,name,sex) VALUES (1,'chigo','M')

INSERT into person (id,name,sex) VALUES (2,'Tony','F')

update person set name = 'vara' , sex = 'F' where id = 1

update person set name = 'Tony' , sex = 'M' where id = 1

update person set name = 'vara' , sex = 'M' where id = 1

DELETE from person where id = 1
INSERT into person_ex SELECT * from person where person.id = 1
update person set name = 'vara' , sex = 'F' where id = 1