mysql触发器 更新记录_mysql触发器trigger实例：记录更新日志信息
mysql触发器实例，记录更新操作的日志信息。
代码如下：
mysql> CREATE TABLE Employee( //创建用于测试的表
-> id int,
-> first_name VARCHAR(15),
-> last_name VARCHAR(15),
-> start_date DATE,
-> end_date DATE,
-> salary FLOAT(8,2),
-> city VARCHAR(10),
-> description VARCHAR(15)
-> );
Query OK, 0 rows affected (0.13 sec)
mysql>
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values (1,'Jason', 'Martin', '19960725', '20060725', 1234.56, 'Toronto', 'Programmer');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(2,'Alison', 'Mathews', '19760321', '19860221', 6661.78, 'Vancouver','Tester');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(3,'James', 'Smith', '19781212', '19900315', 6544.78, 'Vancouver','Tester');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(4,'Celia', 'Rice', '19821024', '19990421', 2344.78, 'Vancouver','Manager');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(5,'Robert', 'Black', '19840115', '19980808', 2334.78, 'Vancouver','Tester');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(6,'Linda', 'Green', '19870730', '19960104', 4322.78,'New York', 'Tester');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(7,'David', 'Larry', '19901231', '19980212', 7897.78,'New York', 'Manager');
Query OK, 1 row affected (0.00 sec)
mysql>
mysql> insert into Employee(id,first_name, last_name, start_date, end_Date, salary, City, Description)
-> values(8,'James', 'Cat', '19960917', '20020415', 1232.78,'Vancouver', 'Tester');
Query OK, 1 row affected (0.01 sec)
mysql>
mysql> select * from Employee; //查询表数据
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| id | first_name | last_name | start_date | end_date | salary | city | description |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| 1 | Jason | Martin | 1996-07-25 | 2006-07-25 | 1234.56 | Toronto | Programmer |
| 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | 6661.78 | Vancouver | Tester |
| 3 | James | Smith | 1978-12-12 | 1990-03-15 | 6544.78 | Vancouver | Tester |
| 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | 2344.78 | Vancouver | Manager |
| 5 | Robert | Black | 1984-01-15 | 1998-08-08 | 2334.78 | Vancouver | Tester |
| 6 | Linda | Green | 1987-07-30 | 1996-01-04 | 4322.78 | New York | Tester |
| 7 | David | Larry | 1990-12-31 | 1998-02-12 | 7897.78 | New York | Manager |
| 8 | James | Cat | 1996-09-17 | 2002-04-15 | 1232.78 | Vancouver | Tester |
+------+------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql> CREATE TABLE transaction_log( //创建日志表
-> user_id VARCHAR(15),
-> description VARCHAR(50)
-> );
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE TRIGGER myTrigger //创建触发器
-> AFTER UPDATE ON employee FOR EACH ROW
-> BEGIN
-> INSERT into transaction_log
-> (user_id, description)
-> VALUES (user(), CONCAT('Adjusted account ',NEW.id,' from ',OLD.salary, ' to ', NEW.salary));
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> update Employee set salary = salary + 1000; //更新数据 触发器工作
Query OK, 8 rows affected (0.00 sec)
Rows matched: 8 Changed: 8 Warnings: 0
mysql>
mysql> drop trigger myTrigger; //删除触发器
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql> select * from transaction_log;
+----------------+--------------------------------------------+
| user_id | description |
+----------------+--------------------------------------------+
| root@localhost | Adjusted account 1 from 1234.56 to 2234.56 |
| root@localhost | Adjusted account 2 from 6661.78 to 7661.78 |
| root@localhost | Adjusted account 3 from 6544.78 to 7544.78 |
| root@localhost | Adjusted account 4 from 2344.78 to 3344.78 |
| root@localhost | Adjusted account 5 from 2334.78 to 3334.78 |
| root@localhost | Adjusted account 6 from 4322.78 to 5322.78 |
| root@localhost | Adjusted account 7 from 7897.78 to 8897.78 |
| root@localhost | Adjusted account 8 from 1232.78 to 2232.78 |
+----------------+--------------------------------------------+
8 rows in set (0.00 sec)
mysql>
mysql> drop table transaction_log; //删除日志表
Query OK, 0 rows affected (0.00 sec)
mysql> drop table Employee; //删除数据表
Query OK, 0 rows affected (0.01 sec)