SQL/MySQL/Trigger/NEW
Содержание
Change NEW value in a before insert trigger
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 (0.02 sec)
mysql>
mysql>
mysql> delimiter $$
mysql>
mysql> CREATE TRIGGER myTrigger
-> BEFORE INSERT ON employee
-> FOR EACH ROW
-> BEGIN
-> DECLARE row_count INTEGER;
->
-> SELECT COUNT(*)
-> INTO row_count
-> FROM employee
-> WHERE id=NEW.id;
->
-> IF row_count > 0 THEN
-> UPDATE employee
-> SET salary = salary+NEW.salary
-> WHERE id=NEW.id;
-> ELSE
-> INSERT INTO employee (id,salary) VALUES(NEW.id,NEW.salary);
-> END IF;
->
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
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");
ERROR 1442 (HY000): Can"t update table "employee" in stored function/trigger because it is already used by statement which invoked this stored function/trigger.
mysql>
mysql> select * from Employee;
Empty set (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql> drop trigger myTrigger;
Query OK, 0 rows affected (0.01 sec)
mysql>
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Checking NEW value and create message
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 (0.08 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 (0.01 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 (0.00 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 $$
mysql> CREATE TRIGGER myTrigger
-> BEFORE UPDATE
-> ON employee
-> FOR EACH ROW
-> BEGIN
-> DECLARE dummy INT;
-> IF NEW.salary<0 THEN
-> SELECT `Account balance cannot be less than 0` INTO dummy
-> FROM employee
-> WHERE id=NEW.id;
-> END IF;
-> END$$
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> drop trigger myTrigger;
Query OK, 0 rows affected (0.02 sec)
mysql>
mysql>
mysql>
mysql> update employee set salary = -1;
Query OK, 8 rows affected (0.01 sec)
Rows matched: 8 Changed: 8 Warnings: 0
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>
Reference new value with NEW in a "BEFORE UPDATE"
mysql>
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 (0.01 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 (0.00 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 $$
mysql> CREATE TRIGGER myTrigger
-> BEFORE UPDATE ON employee
-> FOR EACH ROW
-> BEGIN
-> IF NEW.salary <5000 THEN
-> SET NEW.first_name=CONCAT("NEW.first_name","*");
-> ELSE
-> SET NEW.last_name=CONCAT("NEW.last_name","*");
-> END IF;
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;
mysql>
mysql> update employee set salary = 1000, first_name="new first Name";
Query OK, 8 rows affected (0.01 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 |
+------+-----------------+-----------+------------+------------+---------+-----------+-------------+
| 1 | NEW.first_name* | Martin | 1996-07-25 | 2006-07-25 | 1000.00 | Toronto | Programmer |
| 2 | NEW.first_name* | Mathews | 1976-03-21 | 1986-02-21 | 1000.00 | Vancouver | Tester |
| 3 | NEW.first_name* | Smith | 1978-12-12 | 1990-03-15 | 1000.00 | Vancouver | Tester |
| 4 | NEW.first_name* | Rice | 1982-10-24 | 1999-04-21 | 1000.00 | Vancouver | Manager |
| 5 | NEW.first_name* | Black | 1984-01-15 | 1998-08-08 | 1000.00 | Vancouver | Tester |
| 6 | NEW.first_name* | Green | 1987-07-30 | 1996-01-04 | 1000.00 | New York | Tester |
| 7 | NEW.first_name* | Larry | 1990-12-31 | 1998-02-12 | 1000.00 | New York | Manager |
| 8 | NEW.first_name* | Cat | 1996-09-17 | 2002-04-15 | 1000.00 | Vancouver | Tester |
+------+-----------------+-----------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql> update employee set salary = 6000, last_name="new last Name";
Query OK, 8 rows affected (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 |
+------+-----------------+----------------+------------+------------+---------+-----------+-------------+
| 1 | NEW.first_name* | NEW.last_name* | 1996-07-25 | 2006-07-25 | 6000.00 | Toronto | Programmer |
| 2 | NEW.first_name* | NEW.last_name* | 1976-03-21 | 1986-02-21 | 6000.00 | Vancouver | Tester |
| 3 | NEW.first_name* | NEW.last_name* | 1978-12-12 | 1990-03-15 | 6000.00 | Vancouver | Tester |
| 4 | NEW.first_name* | NEW.last_name* | 1982-10-24 | 1999-04-21 | 6000.00 | Vancouver | Manager |
| 5 | NEW.first_name* | NEW.last_name* | 1984-01-15 | 1998-08-08 | 6000.00 | Vancouver | Tester |
| 6 | NEW.first_name* | NEW.last_name* | 1987-07-30 | 1996-01-04 | 6000.00 | New York | Tester |
| 7 | NEW.first_name* | NEW.last_name* | 1990-12-31 | 1998-02-12 | 6000.00 | New York | Manager |
| 8 | NEW.first_name* | NEW.last_name* | 1996-09-17 | 2002-04-15 | 6000.00 | Vancouver | Tester |
+------+-----------------+----------------+------------+------------+---------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql> drop trigger myTrigger;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
Set NEW value to NULL in a before update trigger
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 (0.02 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 (0.00 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>
mysql> delimiter $$
mysql>
mysql> CREATE TRIGGER myTrigger
-> BEFORE UPDATE ON employee FOR EACH ROW
-> BEGIN
-> DECLARE dummy INT;
->
-> IF NEW.salary<0 THEN
-> SET NEW.salary=NULL;
-> END IF;
->
-> END$$
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> delimiter ;
mysql>
mysql> update employee set salary = -1;
Query OK, 8 rows affected (0.00 sec)
Rows matched: 8 Changed: 8 Warnings: 0
mysql>
mysql> drop trigger myTrigger;
Query OK, 0 rows 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 | NULL | Toronto | Programmer |
| 2 | Alison | Mathews | 1976-03-21 | 1986-02-21 | NULL | Vancouver | Tester |
| 3 | James | Smith | 1978-12-12 | 1990-03-15 | NULL | Vancouver | Tester |
| 4 | Celia | Rice | 1982-10-24 | 1999-04-21 | NULL | Vancouver | Manager |
| 5 | Robert | Black | 1984-01-15 | 1998-08-08 | NULL | Vancouver | Tester |
| 6 | Linda | Green | 1987-07-30 | 1996-01-04 | NULL | New York | Tester |
| 7 | David | Larry | 1990-12-31 | 1998-02-12 | NULL | New York | Manager |
| 8 | James | Cat | 1996-09-17 | 2002-04-15 | NULL | Vancouver | Tester |
+------+------------+-----------+------------+------------+--------+-----------+-------------+
8 rows in set (0.00 sec)
mysql>
mysql>
mysql> drop table Employee;
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql>
mysql>