MariaDB TRIGGER

MariaDB TRIGGER

在MariaDB中只有DELETE,INSERT,UPDATE支持trigger,并且只支持Table,  不支持View

创建trigger

(jlive)[crashcourse]>CREATE TRIGGER newproduct AFTER INSERT ON products FOR EACH ROW BEGIN END;

Query OK, 0 rows affected (0.00 sec)

删除trigger

(jlive)[crashcourse]>DROP TRIGGER newproduct;

Query OK, 0 rows affected (0.00 sec)

trigger只能删除后重建，不能直接修改

INSERT Trigger

CREATE TABLE orders_log

(

change_id int NOT NULL AUTO_INCREMENT,

changed_on datetime NOT NULL,

change_type char(1) NOT NULL,

order_num int NOT NULL,

PRIMARY KEY (change_id)

)ENGINE=Aria;

 

DELIMITER //

CREATE TRIGGER neworder AFTER INSERT ON orders 

FOR EACH ROW

BEGIN

INSERT INTO orders_log(changed_on, change_type, order_num)

VALUES(Now(),'A', NEW.order_num); 

END;//

DELIMITER ;

在AFTER INSERT中有一个特殊的表变更NEW，只要有新记录插入orders表，则在记录插入之后将对就的字段写入到表orders_log中

(jlive)[crashcourse]>INSERT INTO orders(order_date, cust_id) VALUES(Now(), 10001);

Query OK, 1 row affected, 1 warning (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM orders_log;

+-----------+---------------------+-------------+-----------+

| change_id | changed_on          | change_type | order_num |

+-----------+---------------------+-------------+-----------+

|         1 | 2016-03-21 20:37:38 | A           |     20010 |

+-----------+---------------------+-------------+-----------+

 

1 row in set (0.00 sec)

DELETE Trigger

DELIMITER //

CREATE TRIGGER deleteorder BEFORE DELETE ON orders 

FOR EACH ROW

BEGIN

INSERT INTO orders_log(changed_on, change_type, order_num)

VALUES(Now(),'D', OLD.order_num); 

END;//

DELIMITER ;

(jlive)[crashcourse]>DELETE FROM orders WHERE order_num = 20010;

Query OK, 1 row affected, 1 warning (0.00 sec)

(jlive)[crashcourse]>SELECT * FROM orders_log;

+-----------+---------------------+-------------+-----------+

| change_id | changed_on          | change_type | order_num |

+-----------+---------------------+-------------+-----------+

|         1 | 2016-03-21 20:37:38 | A           |     20010 |

|         2 | 2016-03-21 20:41:25 | D           |     20010 |

+-----------+---------------------+-------------+-----------+

 

2 rows in set (0.00 sec)

删除前将OLD表中的对应记录写入到日志表

DELETE前先备份记录

CREATE TABLE orders_archive

(

 order_num int NOT NULL PRIMARY KEY AUTO_INCREMENT,

order_date datetime NOT NULL,

cust_id int NOT NULL

) ENGINE=Aria;

DELIMITER //

CREATE OR REPLACE TRIGGER deleteorder BEFORE DELETE ON orders 

FOR EACH ROW

BEGIN

INSERT INTO orders_log(changed_on, change_type, order_num) VALUES(Now(),'D', OLD.order_num); -- log

INSERT INTO orders_archive(order_num, order_date, cust_id) VALUES(OLD.order_num, OLD.order_date, OLD.cust_id); -- backup

END;//

DELIMITER ;

UPDATE Trigger

(jlive)[crashcourse]>CREATE TRIGGER updatevendor BEFORE UPDATE ON vendors FOR EACH ROW SET NEW.vend_state = Upper(NEW.vend_state);

Query OK, 0 rows affected (0.16 sec)

(jlive)[crashcourse]>UPDATE vendors SET vend_state = 'new york' WHERE vend_id = 1006;               Query OK, 1 row affected (0.01 sec)

 

Rows matched: 1  Changed: 1  Warnings: 0

(jlive)[crashcourse]>SELECT vend_state FROM vendors WHERE vend_id = 1006;

+------------+

| vend_state |

+------------+

| NEW YORK   |

+------------+

 

1 row in set (0.15 sec)