Table of Contents
概念
语法
实例
Home Database Mysql Tutorial Mysql中触发器的使用

Mysql中触发器的使用

Jun 07, 2016 pm 02:50 PM
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概念 触发器是一种特殊的事务,它监听增删改操作,并触发增删改操作。主要是用来处理一些比较复杂的业务逻辑以保证数据的联动性。其包含了四要素:1.监视地点(table) 2.监视事件(insert/update/delete) 3.触发时间(after/before) 4.触发事件(insert/update/d

概念

触发器是一种特殊的事务,它监听增删改操作,并触发增删改操作。主要是用来处理一些比较复杂的业务逻辑以保证数据的联动性。其包含了四要素:1.监视地点(table) 2.监视事件(insert/update/delete) 3.触发时间(after/before) 4.触发事件(insert/update/delete)

语法

<code class=" hljs sql">
<span class="hljs-operator"><span class="hljs-keyword">CREATE</span> <span class="hljs-keyword">TRIGGER</span> <span class="hljs-string">'触发器名称'</span> <span class="hljs-string">'触发时间(after|before)'</span> <span class="hljs-string">'监听的事情(insert|update|delete) '</span>
<span class="hljs-keyword">ON</span> <span class="hljs-string">'触发地点'</span> <span class="hljs-keyword">FOR</span> <span class="hljs-keyword">EACH</span> <span class="hljs-keyword">ROW</span> 
<span class="hljs-keyword">BEGIN</span>
  sql1;</span>
  sql2;
  sql3;
<span class="hljs-operator"><span class="hljs-keyword">END</span>$</span></code>
Copy after login

FOR EACH ROW 用来标识触发器的类型,因为Mysql支持行级别的触发器,不支持语句触发器,故只能使用FOR EACH ROW 。因为触发器中使用’;’区分多个事件语句,故需要重新定义定界符。

实例

修改定界符为$
这里写图片描述
创建触发器
这里写图片描述
查看触发器
这里写图片描述
执行操作之前
t4表数据如下
这里写图片描述
t3表数据如下
这里写图片描述
执行相应的操作之后
这里写图片描述

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