Change the NEW value based on the input in the BEFORE UPDATE trigger : Before Trigger « Trigger « MySQL Tutorial






mysql>
mysql>
mysql> CREATE TABLE Employee(
    ->     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 (0.03 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 (0.02 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;
+------+------------+-----------+------------+------------+---------+-----------+-------------+
| 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>
mysql>
mysql> DELIMITER //
mysql>
mysql> CREATE TRIGGER myTrigger BEFORE UPDATE ON employee
    -> FOR EACH ROW
    -> BEGIN
    ->
    -> IF NEW.id > 5 THEN
    ->     SET NEW.first_name = NEW.first_name+ " *";
    -> END IF;
    ->
    -> IF NEW.salary IS NULL OR NEW.salary = 0 THEN
    ->         SET NEW.salary = 100;
    -> ELSE
    ->         SET NEW.salary = NEW.salary + 100;
    -> END IF;
    ->
    -> END
    ->
    -> //
Query OK, 0 rows affected (0.00 sec)

mysql> DELIMITER ;
mysql>
mysql> update employee set id = 6, first_name= 'new', salary = null;
Query OK, 8 rows affected, 8 warnings (0.00 sec)
Rows matched: 8  Changed: 8  Warnings: 0

mysql>
mysql> select * from employee;
+------+------------+-----------+------------+------------+--------+-----------+-------------+
| id   | first_name | last_name | start_date | end_date   | salary | city      | description |
+------+------------+-----------+------------+------------+--------+-----------+-------------+
|    6 | 0          | Martin    | 1996-07-25 | 2006-07-25 | 100.00 | Toronto   | Programmer  |
|    6 | 0          | Mathews   | 1976-03-21 | 1986-02-21 | 100.00 | Vancouver | Tester      |
|    6 | 0          | Smith     | 1978-12-12 | 1990-03-15 | 100.00 | Vancouver | Tester      |
|    6 | 0          | Rice      | 1982-10-24 | 1999-04-21 | 100.00 | Vancouver | Manager     |
|    6 | 0          | Black     | 1984-01-15 | 1998-08-08 | 100.00 | Vancouver | Tester      |
|    6 | 0          | Green     | 1987-07-30 | 1996-01-04 | 100.00 | New York  | Tester      |
|    6 | 0          | Larry     | 1990-12-31 | 1998-02-12 | 100.00 | New York  | Manager     |
|    6 | 0          | Cat       | 1996-09-17 | 2002-04-15 | 100.00 | Vancouver | Tester      |
+------+------------+-----------+------------+------------+--------+-----------+-------------+
8 rows in set (0.00 sec)

mysql>
mysql> update employee set id = 7, first_name= 'new', salary = 100;
Query OK, 8 rows affected, 8 warnings (0.00 sec)
Rows matched: 8  Changed: 8  Warnings: 0

mysql>
mysql> select * from employee;
+------+------------+-----------+------------+------------+--------+-----------+-------------+
| id   | first_name | last_name | start_date | end_date   | salary | city      | description |
+------+------------+-----------+------------+------------+--------+-----------+-------------+
|    7 | 0          | Martin    | 1996-07-25 | 2006-07-25 | 200.00 | Toronto   | Programmer  |
|    7 | 0          | Mathews   | 1976-03-21 | 1986-02-21 | 200.00 | Vancouver | Tester      |
|    7 | 0          | Smith     | 1978-12-12 | 1990-03-15 | 200.00 | Vancouver | Tester      |
|    7 | 0          | Rice      | 1982-10-24 | 1999-04-21 | 200.00 | Vancouver | Manager     |
|    7 | 0          | Black     | 1984-01-15 | 1998-08-08 | 200.00 | Vancouver | Tester      |
|    7 | 0          | Green     | 1987-07-30 | 1996-01-04 | 200.00 | New York  | Tester      |
|    7 | 0          | Larry     | 1990-12-31 | 1998-02-12 | 200.00 | New York  | Manager     |
|    7 | 0          | Cat       | 1996-09-17 | 2002-04-15 | 200.00 | Vancouver | Tester      |
+------+------------+-----------+------------+------------+--------+-----------+-------------+
8 rows in set (0.00 sec)

mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.02 sec)

mysql>








13.3.Before Trigger
13.3.1.Before insert trigger
13.3.2.Create a 'Before update trigger'
13.3.3.Update table in a before update trigger
13.3.4.Change the NEW value based on the input in a BEFORE INSERT trigger
13.3.5.Change the NEW value based on the input in the BEFORE UPDATE trigger