triggers mysql code example

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 in mysql

CREATE TRIGGER Product_Details_tr 
BEFORE INSERT ON Product_Details 
FOR EACH ROW 
SET NEW.User_ID = CURRENT_USER();

Example 3: creation d'un trigger sql

CREATE OR REPLACE TRIGGER trigg_example
 BEFORE INSERT OR UPDATE ON table_example
 FOR EACH ROW
 WHEN (new.no_line > 0)
 DECLARE
     evol_exemple number;
 BEGIN
     evol_exemple := :new.exemple  - :old.exemple;
     DBMS_OUTPUT.PUT_LINE('  evolution : ' || evol_exemple);
 END;

Example 4: mysql triggers

DELIMITER $$

CREATE TRIGGER before_workcenters_insert
BEFORE INSERT
ON WorkCenters FOR EACH ROW
BEGIN
    DECLARE rowcount INT;
    
    SELECT COUNT(*) 
    INTO rowcount
    FROM WorkCenterStats;
    
    IF rowcount > 0 THEN
        UPDATE WorkCenterStats
        SET totalCapacity = totalCapacity + new.capacity;
    ELSE
        INSERT INTO WorkCenterStats(totalCapacity)
        VALUES(new.capacity);
    END IF; 

END $$

DELIMITER ;