trigger examples mysql

Example 1: trigger in mysql syntax

CREATE TRIGGER trigger_name
{BEFORE | AFTER} {INSERT | UPDATE| DELETE }
ON table_name FOR EACH ROW
trigger_body;

Example 2: trigger stock phpmyadmin output message

DELIMITER $$

CREATE TRIGGER testa_trig  
BEFORE INSERT ON testa 
FOR EACH ROW BEGIN
    IF (NEW.c > 100) THEN 
        SIGNAL SQLSTATE '02000' SET MESSAGE_TEXT = 'Warning: c > 100!';
    END IF;
END$$

DELIMITER ;