SQL - Trigger - wyzwalacz - SQL podstawy

Wyzwalacz (ang. trigger) – procedura wykonywana automatycznie jako reakcja na pewne zdarzenia w tabeli bazy danych. Wyzwalacze mogą ograniczać dostęp do pewnych danych, rejestrować zmiany danych lub nadzorować modyfikacje danych

Trigger - Video -explained 

CREATE TABLE trigger_test(
message VARCHAR (100)
);


DELIMITER $$
CREATE
      TRIGGER my_trigger BEFORE INSERT
      ON employee
      FOR EACH ROW BEGIN
         INSERT INTO trigger_test VALUES ('added new employee');
      END $$
DELIMITER;

Before anything new item will be added to employee table than insert into trigger value "Added new employee" 

DELIMITER change ; into $$ because ; need to be use in TRIGGER what cause end of function

DELIMITER $$

CREATE

    TRIGGER my_trigger1 BEFORE INSERT 

    ON employee

    FOR EACH ROW BEGIN

        IF NEW.sex='M' THEN

            INSERT INTO trigger_test VALUES ('added male employee');

        ELSEIF NEW.sex = 'F' THEN

            INSERT INTO trigger_test VALUES ('added female');

        ELSE

            INSERT INTO trigger_test VALUES ('added other employee');

        END IF;    

    END $$

DELIMITER;   

INSERT INTO employee

VALUES(179, 'Oscar', 'Test', '1968-02-11', 'F', 6900, 106, 3);

INSERT INTO employee

VALUES(180, 'Oscar', 'Bob', '1968-02-11', 'M', 6900, 106, 3);

SELECT * FROM trigger_test;  

http://www.mysqltutorial.org/create-the-first-trigger-in-mysql.aspx

SHOW TRIGGERS;