本文实例讲述了MySQL触发器简单用法。分享给大家供大家参考，具体如下：
mysql触发器和存储过程一样，是嵌入到mysql的一段程序，触发器是由事件来触发的，这些事件包括，INSERT,UPDATE,DELETE，不包括SELECT
创建触发器
|
1
|
CREATE TRIGGER name,time,event ON table_name FOR EACH ROW trigger_stmt |
例如
复制代码 代码如下:
CREATE TRIGGER ins_sum BEFORE INSERT ON account FOR EACH ROW SET @sum = @sum + NEW.amount
有多个执行语句的触发器
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
|
CREATE TABLE test1(a1 INT);CREATE TABLE test2(a2 INT);CREATE TABLE test3(a3 INT NOT NULL AUTO_INCREMENT PRIMARY KEY);CREATE TABLE test4( a4 INT NOT NULL AUTO_INCREMENT PRIMARY KEY, b4 INT DEFAULT 0);DELIMITER //CREATE TRIGGER testref BEFORE INSERT ON test1 FOR EACH ROW BEGIN INSERT INTO test2 SET a2 = NEW.a1; DELETE FROM test3 where a3 = NEW.a1; UPDATE test4 SET b4 = b4 + 1 WHERE a4 = NEW.a1; END //DELIMITER ;INSERT INTO test3(a3) VALUES (NULL), (NULL), (NULL), (NULL), (NULL), (NULL),(NULL), (NULL), (NULL), (NULL), (NULL), (NULL);INSERT INTO test4(a4) VALUES (0), (0), (0), (0), (0), (0), (0), (0), (0), (0);//开始测试INSERT INTO test1 VALUES (1), (3), (1), (7), (1), (8), (4), (4); |
查看触发器
|
1
2
|
SHOW TRIGGERS \G; //查看所有SELECT * FROM information_schema.TRIGGERS where TRIGGER_NAME = 'testref'; |
删除触发器
|
1
|
DROP TRIGGER testref; |
综合案例
步骤1：创建persons表
|
1
|
CREATE TABLE persons (name VARCHAR(40), num int); |
步骤2：创建一个销售额表sales
|
1
|
CREATE TABLE sales (name VARCHAR(40), sum int); |
步骤3：创建一个触发器
|
1
2
|
CREATE TRIGGER num_sum AFTER INSERT ON personsFOR EACH ROW INSERT INTO sales VALUES (NEW.name,7*NEW.num); |
步骤4：向persons表中插入记录
|
1
2
3
|
INSERT INTO persons VALUES ('xiaoxiao',20),('xiaohua',69);SELECT * FROM persons;SELECT *FROM sales; |
希望本文所述对大家MySQL数据库计有所帮助。
原文链接：http://www.cnblogs.com/mr-amazing/p/4679743.html
