DELIMITER |
CREATE TRIGGER version_change BEFORE UPDATE ON documents
FOR EACH ROW
BEGIN
    DECLARE changeDescription varchar(255) default null;
    DECLARE changeName varchar(255) default null;


    IF new.description != old.description THEN
        SET changeDescription = 'Hubo un cambio la Descripcion';
    END IF;

    IF new.name != old.name THEN
        SET changeName = 'Hubo un cambio el Name';
    END IF;

    insert into versions (changes) values(CONCAT(changeDescription, changeName));

END;
|
DELIMITER ;