“MySQL создать триггер” Ответ

MySQL Trigger

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 name_of_trigger [BEFORE|AFTER] [INSERT|UPDATE|DELETE] 
ON test1
FOR EACH ROW
BEGIN
	/* 
    Examples of code to write 
    */
	[INSERT|DELETE|UPDATE|IF|ELSEIF|END IF];
    /* 
    NEW.a1 meanse the new value that will be added with INSERT into test1
    */
    INSERT INTO test2 SET a2 = NEW.a1;
    DELETE FROM test3 WHERE a3 = NEW.a1;
    UPDATE test4 SET b4 = b4 + 1 WHERE a4 = NEW.a1;
    IF NEW.a1 < 0 THEN
    	SET NEW.a1 = 0;
    ELSEIF NEW.a1 > 100 THEN
    	SET NEW.a1 = 100;
    END IF;
END//
delimiter;
Hou

MySQL создать триггер

CREATE DEFINER=`root`@`localhost` TRIGGER increment_animal
  AFTER INSERT ON animals FOR EACH ROW
    UPDATE animal_count SET animal_count.animals = animal_count.animals+1;
ERROR 1359 (HY000): Trigger already exists

CREATE OR REPLACE DEFINER=`root`@`localhost` TRIGGER increment_animal
  AFTER INSERT ON animals  FOR EACH ROW
    UPDATE animal_count SET animal_count.animals = animal_count.animals+1;
Query OK, 0 rows affected (0.12 sec)

CREATE DEFINER=`root`@`localhost` TRIGGER IF NOT EXISTS increment_animal
  AFTER INSERT ON animals FOR EACH ROW
    UPDATE animal_count SET animal_count.animals = animal_count.animals+1;
Query OK, 0 rows affected, 1 warning (0.00 sec)

mysql [localhost] {msandbox} (test) > SHOW WARNINGS;
+-------+------+------------------------+
| Level | Code | Message                |
+-------+------+------------------------+
| Note  | 1359 | Trigger already exists |
+-------+------+------------------------+
1 row in set (0.00 sec)
Singh99

Ответы похожие на “MySQL создать триггер”

Вопросы похожие на “MySQL создать триггер”

Больше похожих ответов на “MySQL создать триггер” по Sql

Смотреть популярные ответы по языку

Смотреть другие языки программирования